Click for next page ( 31


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 30
31 APPENDIX A Discussion of Topic Issues CHAPTER TWO: HEALTH EFFECTS associations are weak and the effect is somewhat stronger for OF AVIATION NOISE ischemic heart disease than for hypertension. Nevertheless, such small risks are potentially important because a large number of Determination of the effects of aviation noise on health is an persons are currently exposed to these noise levels, or are likely to be exposed in the future. intricately complex and notoriously difficult field of study. Variations on how to identify and/or measure the noise Another example is a study by Passchier-Vermeer and exposure (single dose, long-term average, number of events Passchier (2000) that reviewed existing literature and states above a certain level, etc.) and attempting to separate these that there is sufficient scientific evidence that noise exposure effects from other life events is a difficult task. For example, can induce hearing impairment, hypertension, and ischemic lifestyles, life's stressors, hereditary factors, and genetic heart disease. The authors concluded that there are "no composition are just a few factors that may distort potential obvious effects from noise exposure on mean diastolic and results of an aviation noise health effects study. mean systolic blood pressure, but some effects were observed in terms of an increase in the percentage of people Given this complexity, the large amount of research pub- with hypertension (including those who use medication for lished during the last 30 years has produced considerable hypertension)" (Passchier-Wermeer and Passchier 2000). variability of results; often, some are quite controversial. The The observation threshold for hypertension is estimated to absence of one internationally accepted "exposure-effect" correspond to an Ldn value of 70 dB(A) for environmental (or "dose-response") relationship is largely the result of a noise exposure. lack of one obvious "best choice" research methodology, as well as to the complex interactions of the many factors that Most reviewers concluded that previous reviews were not influence aviation noise effects. These include differences in carried out in a systematic way, which makes them prone to the characteristics of the noise itself, differences in individ- bias. Reviewers point out the tendency for some studies to ual sensitivities, differences in attitudinal biases toward the inadequately report noise exposure data. With respect to the noise source, and variations in living environments. association between noise exposure and blood pressure, small blood pressure differences were evident. Van Kempen et al. Considerable research, review of previous research with (2002) stated: "Although we can conclude that noise exposure new thought, new independent research, and collaborative can contribute to the prevalence of cardiovascular disease, the efforts to identify health effects related solely to aviation evidence for a relation between noise exposure and ischemic noise have been completed; most can be condensed into heart disease is still inconclusive because of the limitations impacts in three primary categories: the cardiovascular of exposure characterization, adjustment for important con- system, children, and hearing impairment. founders, and the occurrence of publication bias." Cardiovascular Effects Cross-sectional studies, such as that by Goto and Kaneko (2002), who observed blood pressure in general health Several recent studies have reviewed previous literature, either examination data from around a city airport and then compared through compilation or re-review of original data, which the data with that from a calm suburban area of the city, showed suggests that increased hypertension or other cardiovascular that systolic and diastolic blood pressure was not associated effects may be associated with particular long-term noise with aircraft noise levels in the area. exposure. For example, the World Health Organization's (WHO's) Guidelines for Community Noise (2000), presented Recent studies by Eriksson et al. (2007) and Jrup et al. at the WHO Expert Task Force meeting, finds that: (2007) have reported higher rates of hypertension with increasing aircraft noise levels. The HYENA study identified . . . the overall evidence suggests a weak association between that the effect occurred only for night-time aircraft noise. long-term environmental noise exposure and hypertension, and no dose-response relationships could be established . . . The overall conclusion is that cardiovascular effects are associated It should be noted that cross-sectional studies are notori- with long-term exposure to LAeq 24 h values in the range of 6570 ously difficult to interpret, because they often report con- dB or more, for both air- and road traffic noise. However, the flicting results, generally do not identify a cause and effect

OCR for page 30
32 relationship, and often do not report a dose-response rela- conducted where environmental noise does not appear to ap- tionship between the cause and effect. proach recognized occupational noise limits. Further, it may be that the intermittency of environmental noise itself may protect hearing from damage (Sixsmith and Wheeler 1999). Aviation Noise Effects and Children The conclusion that environmental noise does not have an Another particular concern over the past 30 years is the effect on hearing threshold levels, particularly that environ- potential health effect on children resulting from exposure to mental noise does not approximate occupational noise levels or or interference from aviation noise. One cross-sectional study recreational noise exposures (e.g., personal listening devices, by Poustka et al. (1992) studies psychiatric disorders on discotheques, motorcycles, and pop concerts) is also echoed in children aged 4 to 16 years in two contrasting geographic several other studies. Lastly, studies have also shown that early regions using cross-sectional analyses of the two regions. noise exposure as a child on military jet aircraft bases does not Although noise levels were not reported, they are likely to be make one more susceptible to noise-induced hearing loss. very high because military aircraft fly as low as 75 m with very Ludlow and Sixsmith (1999) state that "this study has found high onset rates. Neither psychiatric disorders nor environ- no evidence that RAF personnel who have lived on or near fast mental factors showed any relationship to noise; however, jet stations while very young display raised hearing threshold psychophysiological parameters (e.g., heart rate and muscle levels associated with noise-induced hearing loss." tension) demonstrated some relationship to noise. Other recent studies have focused on the relationships Summary between noise exposure during pregnancy and low birth weights. Wu et al. (1996) analyzed the effect of total noise In the more than 20 years since publication of the FAA's exposure during pregnancy on infant birth rate. No association Aviation Noise Effects document there has been consider- between personal noise exposure measured in decibels (less able research, review of previous research with new thought, than 85 dBA Leq during pregnancy) and birth weight was found. and new independent research, as well as collaborative Possible occupational noise, traffic noise exposure, or a history efforts to identify health effects related to aviation noise. of listening to amplified music using personal listening devices Some studies have identified a potential correlation between during pregnancy also showed no effect on infant birth weight. increased hypertension and aviation or road noise above certain noise thresholds [typically a day-night average noise Hospitals and Care Facilities level (DNL) value of 70 dBA]; however, other studies contradict such findings. Occupational noise often becomes A careful search of recent research regarding aviation noise an intricate concern. Health effects on children, particularly and hospitals and care facilities identified no studies that those with decreased cognitive abilities, mental distur- addressed this specific issue. It is common for airport bances, or other psychological stressors, and studies of preg- noise/land-use compatibility guidelines to list hospitals and nancy and low infant birth weights, all indicate there is no care facilities as noise-sensitive uses, although there are no correlation between aviation noise and childhood psychi- studies that have identified health effects associated with avia- atric disorders, environmental factors, or low infant birth tion noise. There are numerous studies that identify problems weights. Additionally, recent studies have concluded that with internal hospital noises such as warning alarms, pagers, aviation noise does not pose a risk factor for child or teenage gurney collisions with doors, talking, etc.; however, none that hearing loss, but perhaps other noise sources (e.g., personal addressed aviation or roadway noise. WHO included a discus- music devices, concerts, motorcycles, and night clubs) are a sion of hospital noise in its Guidelines for Community Noise primary risk factor. Because aviation and typical community (2000) (Section 4.3.3 of WHO Guidelines addresses hospital noise levels near airports are not comparable to the occupa- noise levels in general terms and does not provide any specific tional or recreational noise exposures associated with guidance relative to aircraft noise). hearing loss, hearing impairment resulting from community aviation noise has not been identified. Hearing Impairment Aviation noise exposure and potential hearing impairment Although newer studies suggest there may be a potential during all ages of life are also a common research effort. Re- relationship between aviation noise levels and hypertension search in this area is much more definitive, often owing to or ischemic heart disease at noise levels as low as 50 dBA Leq adequate controls, data, and identifiable conclusions. One study, (Eriksson et al. 2007), further research is necessary. Among Sixsmith and Wheeler (1999) on auditory impact, reviewed the confounding factors in studies of hypertension and air- nine studies done in the vicinity of seven civil and military air- craft noise is that aircraft noise exposure is taken from noise ports and two laboratory studies. model estimates without regard to ambient noise levels. The ambient noise levels in urban areas and most suburban areas The laboratory studies suggest that permanent threshold shifts exceed 50 dBA Leq. Furthermore, only a handful of recent are unlikely to be induced by exposures to aircraft noise thought studies of populations near airports attempted to segregate to be typical of real life. . . . In the main, these studies have been health effects of noise from that of air pollution.

OCR for page 30
33 Despite decades of research, including reviews of old data The results showed that "for subjects exposed to energy- and multiple new research efforts, health effects of aviation averaged levels above 50 dB(A) the adjusted relative risk for noise continue to be an enigma. Most, if not all, current hypertension was 1.19. . . . Maximum aircraft noise levels research concludes that despite well-founded hypotheses it is presented similar results, with a relative risk of 1.20 . . . for as yet impossible to determine causal relations between those exposed above 70 dB(A)." The authors went on to con- health disorders and noise exposure. clude that "these findings suggest that long-term aircraft noise exposure may increase the risk for hypertension." The Annotated Bibliography--Health Effects authors also state that this type of longitudinal study would of Aviation Noise tend to be more reliable than the typical cross-sectional study on hypertension. However, although it is true that the study Babisch, W., Transportation Noise and Cardiovascular included the same subjects in the 19921994 and 20022004 Risk, Federal Environmental Agency, Berlin, Germany, surveys, the results for subjects near the airport were 2006, 113 pp. compared with subjects farther from the airport. The study is subject to the problems of a cross-sectional study in which This German Federal Environmental Agency study presents a subjects in one area of noise exposure are compared with comprehensive review of transportation noise and cardiovas- subjects in a different area of noise exposure. Furthermore, cular risk. The study uses published reports and presents no the study results identified increased hypertension at noise new study data. The author states that according to the general levels as low as 50 dBA Leq, which is lower than typical stress concept, repeated autonomic and endocrine responses ambient noise levels in urban areas and lower than ambient can result in permanent functional and metabolic changes of noise levels in many suburban areas. the organism in chronically exposed subjects. Epidemiologi- cal studies suggest a higher risk of cardiovascular diseases Finegold, L.S., S. Job, R. de Jong, and B. Griefahn, "The including high blood pressure and myocardial infarction in Effect of Noise on Public Health: International Congress subjects chronically exposed to high levels of road or air- Explores Global Impact," The ASHA Leader, Oct. 5, traffic noise. Sixty-one epidemiological noise studies were 2004, pp. 67, 13. evaluated regarding the relationship between transportation noise and cardiovascular outcomes. The author is careful to This is a two-part series describing the research and findings separate studies and results for road noise from those that presented at the Eighth International Congress in Rotterdam, included aircraft noise. "With respect to aircraft noise and The Netherlands, in 2004 on Noise as a Public Health hypertension, studies consistently show higher risks in higher Problem. The Congress, which is held every five years, is exposed areas." The data for these studies tend to show that sponsored by the International Commission on Biological the effect threshold is a DNL of 60 dBA. "With regard to Effects of Noise and is organized into nine noise teams. The ischemic heart disease [IHD], the evidence of an association team on non-auditory physiological effects reported on current between community noise and IHD risk has increased since a studies. Recent years have focused on cardiovascular research previous review. There is not much indication of a higher IHD and on the effects of noise on children. Studies of environ- risk for subjects who live in areas with a daytime average mental noise appear to predict both hypertension and coronary sound pressure level of less than 60 dBA." The author notes heart disease, although self-report outcomes are probably that "statistical significance was rarely achieved." insufficient in this area. Further consideration is needed in assessing environmental stressors such as air pollution, which Eriksson, C., M. Rosenlund, G. Pershagen, A. Hilding, frequently accompanies noise pollution. C. Ostenson, and G. Bluhm, "Aircraft Noise and Inci- dence of Hypertension," Epidemiology, Vol. 18, No. 6, Franssen, E.A.M., C.M.A.G. van Wiechen, N.J.D. 2007, pp. 716721. Nagelkerke, and E. Lebret, "Aircraft Noise Around a Large International Airport and Its Impact on General This study of hypertension near Stockholm Arland Airport Health and Medication Use," Journal of Occupational was conducted from 1992 through 1994 and again with the and Environmental Medicine, Vol. 61, 2004, pp. 405413. same subjects from 2002 through 2004. The study group was based on the Stockholm Diabetes Preventive Program; half of The authors assess the prevalence of general health status, use the study subjects had a family history of diabetes. Residen- of sleep medication, and use of medication for cardiovascular tial aircraft noise exposure (expressed as time-weighted equal diseases, and study their relation to aircraft noise exposure energy and maximal noise levels) was assessed by geo- around Schipol Airport (Amsterdam). These health indicators graphical information systems (GIS) techniques among those were measured by a cross-sectional survey (self-report ques- living near the airport. Incident cases of hypertension were tionnaire) among 11,812 respondents living within a radius of identified by physical examinations, including blood pressure 25 km of the airport. The authors calculated the odds ratio for measurements, and questionnaires in which subjects reported each effect and associated an increasing effect with increasing treatment or diagnosis of hypertension and information on Lden [DNL with a 5 dBA evening weighting, identical to the cardiovascular risk factors. community noise equivalent level (CNEL) metric used in

OCR for page 30
34 California]. The associations were statistically significant for Griefahn, B., "Noise-Induced Extraaural Effects," The all indicators, except for use of prescribed sleep medication or Journal of the Acoustical Society of Japan (E), Vol. 21, sedatives and frequent use of this medication. None of the 2000, pp. 307317. health indicators were associated with aircraft noise exposure during the night, but use of non-prescribed sleep medication The paper presents a state-of-the-art summary concerning the or sedatives was associated with aircraft noise exposure dur- extraaural effects of noise. The study is based on a review of ing the late evening. Vitality-related health complaints such other studies and no new research data are presented. The as tiredness and headache were associated with aircraft noise, analysis is presented in terms of primary effects that occur dur- whereas most other physical complaints were not. A small ing the period of noise exposure [e.g., speech interference (SI), fraction of the prevalence of poor self-rated health (13%), sleep disorders, and altered autonomous functions], secondary medication for cardiovascular diseases or increased blood effects (e.g., annoyance, degraded well-being, and perfor- pressure (8%), and sleep medication or sedatives (22%) might mance), and tertiary effects (long-term health effects; e.g., be attributed to aircraft noise. Although the authors concluded hypertension or cardiovascular diseases). The study concludes that the results suggest an association between community that it was as yet impossible to determine causal relations exposure to aircraft noise and indicators of poor general between health disorders and noise exposures despite well- health status, use of sleep medication, and use of medication founded hypotheses. The author identified studies that show for cardiovascular diseases, the data are more complex than the threshold for higher risk for hypertension to be "day-time this conclusion indicates. For example, the odds ratios for outdoor levels of considerably more than 80 dBA," although cardiovascular diseases or increased blood pressure medica- "the reviewers determined the respective thresholds of at least tion increase for populations exposed to Lden levels in the 70 dBA for hypertension and between 65 and 70 dBA for 50 to 55 dBA range; it increases yet again for populations in ischemic heart diseases." The author noted that difficulties to the 55 to 60 dBA range, but decreases for the population determine causal relations increase with the time lag between above 60 Lden. When the populations were divided into two the onset of noise exposure and the manifestation of an effect groups, one with noise exposures less than 51 Lden and the in question. Another important factor is habituation, which other with noise exposures more than 59 Lden, percentages of causes a reduction of primary and secondary responses with the population reporting a health effect were identical or dif- time. The significance of these contributors in view of the hy- ferent by only 1% for each group. The method that the pothesized health effects must be elucidated in future studies. authors used to segregate out the fraction of the population Other topics for future research are discussed as well. reporting a health effect that is associated with aircraft noise is unclear. Guidelines for Community Noise, Presented at the WHO Expert Task Force Meeting, B. Berglund, T. Lindvall and Goto, K. and T. Kaneko, "Distribution of Blood Pressure D.H. Schwela, eds., London, United Kingdom, 2000. Data from People Living near an Airport," Journal of Sound and Vibration, Vol. 250, No. 1, 2002, pp. 145149. In 2000, the WHO published its Guidelines for Community Noise, which was assembled by a team of international experts This cross-sectional study observed blood pressure in general including two members from the United States. It includes health examination data in the vicinity of a city airport and chapters on noise sources and noise measurement, adverse compared the data with those from a calm suburban area of the health effects of noise, guideline values, noise management city. Information was also collected on the short-term history strategies, and conclusions. The report addresses all forms of of medication and lifestyle including smoking, drinking, and noise including industrial, transportation, construction, eating salty foods. This cross-sectional study on 469 women domestic activities, and leisure activities. The Guidelines showed that systolic and diastolic blood pressure was not describe various noise metrics and their application. In terms associated with aircraft noise levels in the area, even after con- of health effects, it describes hearing loss, interference trolling for variables regarding anti-hypertension treatment with speech, sleep disturbance, cardiovascular and physiolog- and lifestyle factors. A comparative study on 469 women from ical effects, mental health effects, performance effects, and an area around an airport and 1,177 women from a suburban annoyance. The report does not contain any original research, control area showed no significant difference between blood but is a comprehensive review of available literature available pressure and other medical tests controlling for the variables as of April 1999. In terms of cardiovascular and physiological of medication and lifestyle. Changes in blood pressure after effects the report finds 8 years were observed in 183 women around the airport. No significant differences among three zones with different levels . . . only a few studies on environmental noise have shown that pop- of aircraft noise were found. The three noise zones used in the ulations living in noisy areas around airports and on noisy streets study were less than 75 WECPNL (Weighted Equivalent Con- have an increased risk for hypertension. The overall evidence tinuous Perceived Noise Level) (~60 DNL), between 75 and 90 suggests a weak association between long-term environmental WECPNL (~60 and ~77 DNL), and greater than 90 WECPNL noise exposure and hypertension, and no dose-response rela- tionships could be established. . . . The overall conclusion is that (~77 DNL). The authors do not provide noise level data for the cardiovascular effects are associated with long-term exposure to control group in the suburban control area. LAeq, 24h values in the range of 6570 dB or more, for both air and

OCR for page 30
35 road traffic noise. However, the associations are weak and the in the first study reports. For night-time aircraft noise, a 10 dB effect is somewhat stronger for ischemic heart disease than for increase in exposure was associated with an odds ratio (OR) of hypertension. Nevertheless, such small risks are potentially im- portant because a large number of persons are currently exposed to 1.14. OR is computed from the odds of one group having a con- these noise levels, or are likely to be exposed in the future. dition to the odds of another group having that condition. The Furthermore, only the average risk is considered and sensitive exposure-response relationships were similar for road traffic subgroups of the populations have not been sufficiently character- noise and stronger for men. The results indicate excess risks of ized. Other observed psychophysiological effects, such as changes in stress hormones, magnesium levels, immunological indicators, hypertension related to long-term noise exposure, primarily for and gastrointestinal disturbances are too inconsistent for conclu- night-time aircraft noise and daily average road traffic noise. sions to be drawn about the influence of noise pollution. A closer review of the HYENA data for night-time aircraft noise raises some questions about the data. Figure A1 shows Harris, C., The Effects of Noise on Health, U.S. Air Force, the OR plotted as a function of the night-time aircraft Leq. The Armstrong Laboratory, WrightPatterson Air Force dashed line is the trendline. The highest OR occurs in the range Base, Ohio, 1997, 56 pp. of night Leq from 40 to 44 dBA and decreases at higher ex- posures. Note that the first two data points, OR values near 1 This is a comprehensive report on the health effects of noise. (no effect on hypertension) at noise exposures less than Both environmental noise and occupational noise exposure 40 dBA, have a significant effect on the trendline. If the first are examined. It contains no original research, but is a very two no-effect data points are eliminated from the regression good compilation of research done through 1997 and includes analysis, the trendline reverses slope (decreasing odds of hy- extensive critical review of the available literature. The author pertension with increasing noise level), a result not addressed comments on the extent and quality of health-related research by the authors. Note that the authors used modeled noise levels and finds much of the research to be lacking. After some for this study and report night-time outdoor noise levels as low expert opinion on the health effects of noise, there is an attempt as 30 dBA. This is the aircraft contribution to the overall ambi- to convey the complexity of the difficulties in forming a per- ent noise level and the ambient noise level is most likely higher spective on noise research. This is followed, in turn, by a than this. This may explain the OR values near 1 (meaning no discussion of some of the early research sponsored by the effect on hypertension) at the lower noise levels. EPA. Next is a discussion of noise-induced physiological changes, noise as a stressor, and some specialized topics re- Jrup, L., M.L. Dudley, W. Babisch, D. Houthuijs, garding the effects of impulsive acoustic stimuli, the effects W. Swart, and G. Pershagen, "Hypertension and Exposure on sleep, on hearing, and on people living under military train- to Noise near Airports (HYENA): Study Design and Noise ing routes. Finally, an attempt is made to summarize, evaluate, Exposure Assessment," Environmental Health Perspectives, and take a position relative to health effects of noise. The Vol. 113, No. 11, Nov. 2005, pp. 14731478. author identified a number of studies that focus on the rela- tionship between cardiovascular disease and noise exposure, The Hypertension and Exposure to Noise near Airports which identify the inconsistency of the results. The author (HYENA) project aims to assess the impact of airport-related points out that the only two effects that result directly from noise exposure on blood pressure and cardiovascular disease aircraft noise are hypertension and ischemic heart disease." The using a cross-sectional study design. The study includes 6,000 relative risk of ischemic heart disease and of hypertension persons (45 to 70 years old) who had lived for at least five starts to increase for persons living in areas with road or air- years near one of six major European airports. Modeled traffic noise at equivalent sound levels above 70 dB(A)." aircraft noise contours were used with the intent of maximiz- ing exposure contrast. Automated blood pressure instruments Jrup, L., et al., "Hypertension and Exposure to Noise were used to reduce observer error. A standardized question- near Airports--The HYENA Study," Environmental naire was used to collect data on annoyance, noise disturbance, Health Perspectives, Vol. 116, No. 3, pp. 329333 [Online]. and major confounders. Cortisol in saliva was collected in a Available: doi:10.1289/ehp.10775 (available at http:// subsample of the study population (n = 500) stratified by noise dx.doi.org/), Dec. 11, 2007. exposure level. To investigate short-term noise effects on blood pressure and possible effects on night-time blood pres- This study measured blood pressure and collected data on sure dipping, 24-h blood pressure was measured and assessed health, socioeconomic, and life-style factors, including diet and with continuous noise models in another subsample (n = 200). physical activity, for 4,861 persons aged 45 to 70 years who had To ensure comparability between countries, common noise lived at least five years near any of six major European airports. models were used to assess individual noise exposure, with a Noise exposure was assessed using noise models with a resolu- resolution of 1 dBA. Modifiers of individual exposure, such as tion of 1 dB (5 dB for UK road traffic noise). The authors found the orientation of living rooms and bedrooms toward roads, significant exposure-response relationships between night-time window-opening habits, and sound insulation, were assessed aircraft noise as well as average daily road traffic noise expo- by the questionnaire. For four airports, estimated exposure to sure and risk of hypertension after adjustment for major air pollution was used to explore modifying effects of air confounders. Note that the HYENA study data analysis is pollution on cardiovascular disease. The project assesses ex- ongoing and that air pollution as a confounder was not analyzed posure to traffic-related air pollutants, primarily using data

OCR for page 30
36 FIGURE A1 Odds ratio for hypertension versus night-time aircraft noise (adapted from Figure 2 of HYENA Study, Jarup et al. 2007). from another project funded by the European Union. This mental health effects, and effects on wildlife. In terms of health study is one of the very few attempting to segregate the health effects, the report concludes that most studies include limited effects caused by noise or air pollution near airports. The study data with no definitive conclusions. With respect to cardiovas- results were scheduled to be published in the fall of 2007. cular effects, the report concludes that such effects are associated with long-term exposure to daily equivalent sound Two HYENA studies were published in early 2008, too late levels greater than 65 dB. for full consideration in this synthesis. These studies (Jarup et al. 2007 and Haralabidis et al. 2008) present results indicat- Passchier-Vermeer, W. and W.F. Passchier, "Noise ing "excess risks of hypertension related to long-term noise Exposure and Public Health," Environmental Health exposure primarily for night-time aircraft noise and daily Perspectives, Vol. 108, No. 1, Mar. 2000, pp. 123131. average road traffic noise" (Jarup et al. 2008). "Effects of noise exposure on elevated subsequent BP measurements This journal article presents a broad discussion of existing were clearly shown. The effect size of the noise level appears to literature on the health effects of noise, including environmen- be independent of the noise source" (Haralabidis et al. 2008). tal and occupational exposures. The authors report that there is sufficient scientific evidence that noise exposure can induce Lee, C.S.Y. and G.G. Fleming, General Health Effects of hearing impairment, hypertension, ischemic heart disease, Transportation Noise, U.S. Department of Transporta- annoyance, sleep disturbance, and decreased school perfor- tion, Washington, D.C., June 2002, 44 pp. mance. The evidence is limited for other effects, such as changes in the immune system and birth defects. A subject for The FRA sponsored the preparation of this report to support a further research is the elucidation of the mechanisms underly- rulemaking process about the use of locomotive horns and the ing noise-induced cardiovascular disorders and the relation- accompanying environmental impact statement. This docu- ship of noise with annoyance and non-acoustical factors ment reviews select current and past research on the effect of modifying health outcomes. A high-priority study subject is transportation noise on the physiological and psychological the effect of noise on children, including cognitive effects, and health of both people and wildlife. This is a short and easy- its reversibility. With respect to aircraft and road noise and to-read report that does not contain any original research, but hypertension and ischemic heart disease, the authors conclude rather relies on reports published through the year 2000. The that there are "no obvious effects from noise exposure on mean subjects covered include annoyance, SI, effects on perfor- diastolic and mean systolic blood pressure, but some effects mance, interference with recreational activities, hearing loss, were observed in terms of an increase in the percentage of sleep disturbance, muscular effects, cardiovascular effects, people with hypertension (including those who use medication

OCR for page 30
37 for hypertension). The observation threshold for hypertension made adjustments is needed. With respect to the association is estimated to correspond to an Ldn value of 70 dB(A) for between noise exposure and blood pressure, small blood pres- environmental noise exposure." Studies of the cardiovascular sure differences were evident. The meta-analysis showed a effects of noise on children are less clear; therefore, the authors significant association for both occupational noise exposure recommend further study. The authors also cite studies on the and air-traffic noise exposure and hypertension, although the effects of noise on birth weight and conclude that noise expo- conclusion, with respect to air traffic, was derived from a sin- sure is not related to birth weight. gle study done in 1976. Occupational exposure to noise and hypertension was identified in numerous studies. Air traffic Rosenlund, M., N. Berglind, G. Pershagen, L. Jrup, and noise exposure was positively associated with the consultation G. Bluhm, "Increased Prevalence of Hypertension in a of a general practitioner or specialist, the use of cardiovascular Population Exposed to Aircraft Noise," Journal of Occu- medicines, and angina pectoris. In cross-sectional studies, road pational and Environmental Medicine, Vol. 58, 2001, traffic noise exposure increases the risk of myocardial infarc- pp. 769773. tion and total ischemic heart disease. Only 2 of the 43 studies attempted to quantify the relation between noise and cardio- This study used a cross-sectional analysis to investigate vascular disease. "Although we can conclude that noise whether there is a relation between residential exposure to exposure can contribute to the prevalence of cardiovascular aircraft noise and hypertension. The study was done by the disease, the evidence for a relation between noise exposure Department of Environmental Health, Stockholm County and ischemic heart disease is still inconclusive because of the Council, Sweden. The study population was comprised of two limitations of exposure characterization, adjustment for im- random samples of subjects aged 19 to 80 years, one including portant confounders, and the occurrence of publication bias." 266 residents in the vicinity of Stockholm Arlanda airport and The authors recommended further study. another comprising 2,693 inhabitants in other parts of Stock- holm County. The subjects were classified according to the Aviation Noise Effects and Children time weighted equal energy and maximum aircraft noise lev- els at their residence. A questionnaire provided information on Poustka, F., P. Eckermann, and K. Schmeck, "Effect of individual characteristics including history of hypertension. Aircraft Noise and Psychosocial Stressors on Mental The prevalence odds ratio for hypertension adjusted for age, Disturbances of Children and Adolescents: An Epide- sex, smoking, and education was higher among those with miological Survey in Westphalia," In Developmental energy-averaged aircraft noise levels exceeding 55 dBA, and Psychopathology, H. Remschmidt and M.H. Schmidt, among those with maximum aircraft noise levels exceeding eds. Hogrefe and Huber Publishers, 1992, pp. 8396. 72 dBA. An exposure-response relation was suggested for both exposure measures. The exposure to aircraft noise ap- In this chapter the authors report on psychiatric disorders in peared to be particularly important for older subjects and for children aged 4 to 16 years. The children were studied in two those not reporting impaired hearing ability. The study con- contrasting geographic regions using a cross-sectional analy- cludes that community exposure to aircraft noise may be asso- sis of two regions. These regions differed according to the ciated with hypertension. noise made by jetfighters exercising frequently at low altitude. Noise levels are not reported, but are likely very high because Van Kempen, E., H. Kruize, H.C. Boshuizen, C.B. Ame- these military aircraft fly as low as 75 m with very high onset ling, B. Staatsen, and A. de Hollander, "The Association rates. Psychosocial and individual variables known to act as Between Noise Exposure and Blood Pressure and potential risk factors for psychiatric disorders correlate highly Ischemic Heart Disease: A Meta-Analysis," Environ- with psychiatric disorders. The correlation between adverse mental Health Perspectives, Vol. 110, No. 3, Mar. 2002, factors and symptoms differed between age and gender pp. 307317. samples. Neither psychiatric disorders nor environmental factors showed any relationship to noise; however, psycho- The authors conducted a meta-analysis of 43 epidemiological physiological parameters (e.g., heart rate and muscle tension) studies published between 1970 and 1999 that investigated the demonstrated some relationship to noise. Their meaning is un- relation between noise exposure (both occupational and com- certain and warrants further research. munity) and blood pressure and/or ischemic heart disease. It has been suggested that noise exposure is associated with Wu, T.N., L.J. Chen, J.S. Lai, G.N. Jo, C.Y. Shen, and P.Y. blood pressure changes and ischemic heart disease risk, but Chang, "Prospective Study of Noise Exposure During epidemiological evidence is still limited. Most reviews inves- Pregnancy on Birth Weight," American Journal of Epi- tigating these relations were not carried out in a systematic demiology, Vol. 143, No. 8, 1996, pp. 792796. way, which makes them more prone to bias. The authors stud- ied a wide range of effects, from blood pressure changes to This study does not address aircraft noise specifically, but the myocardial infarction. They pointed out the tendency for some total noise exposure to all noise sources during the day. To studies to inadequately report noise exposure data; therefore, examine the effect of noise exposure during pregnancy on they included an evaluation of the noise exposure data and infant birth weight, a well-characterized cohort of 200 pregnant

OCR for page 30
38 women in the first trimester participating in a prenatal care impairment other than that owing to noise (with allowance for clinic was followed throughout gestation in Taiwan in 1991. the effects of age) or of unscreened populations whose hearing Individual 24-h noise exposure of all women was prospec- capability has been measured or estimated. The standard spec- tively measured using a personal dosimeter, and information ifies a method of calculating the expected noise-induced regarding possible noise exposure from traffic and occupation permanent threshold shift in the hearing threshold levels of was also obtained. Noise exposure during pregnancy was adult populations resulting from various levels and durations correlated with the birth weights of the women's babies. No of noise exposure. The standard does not address specific noise association between personal noise exposure measured in sources such as aircraft noise. The methodology employed is decibels (less than 85 dBA Leq during pregnancy) and birth somewhat complex, but is useful for considering the potential weight was found. Possible occupational noise exposure for hearing loss from environmental exposure to aircraft noise. (indicated by working in a manual job), traffic noise exposure Typical community noise levels near an airport are not com- (indicated by the distance between the home and main streets), parable to the occupational or recreational noise exposures that and a history of listening to amplified music and using per- are associated with hearing loss. sonal listening devices during pregnancy also showed no effect on infant birth weight. Maternal weight, maternal weight Ludlow, B. and K. Sixsmith, "Long-Term Effects of gained during pregnancy, gestational age, and the infant's sex Military Jet Aircraft Noise Exposure During Childhood were the four factors that correlated significantly with birth on Hearing Threshold Levels," Noise and Health, Vol. 5, weight. The study concluded that the noise exposure experi- 1999, pp. 3339. enced by women during pregnancy may not be great enough to affect their infants' birth weight. This study evaluates suggestions that young children may be relatively more susceptible to noise-induced hearing loss than Hospitals and Care Facilities adults, and that the unique noise footprint associated with military jet aircraft is particularly damaging to hearing. This See WHO, Guidelines for Community Noise (2000) in previous pilot study looked for evidence of noise-induced hearing loss section. in adults who have been exposed to military jet noise in early childhood, while living in married quarters on active Royal Hearing Impairment Air Force fast jet stations. Many of the subjects lived in quar- ters that lie within 70 dBA Leq contours, with a few in 83 dBA Finegold, L.S., A. Muzet, B.F. Berry, and M.S. Finegold, Leq contours. A cross-sectional pilot study was undertaken to Effects of Aircraft Noise on Communities: Sleep Disturbance examine the hypothesis that military jet noise exposure early and Hearing Loss, Japan Defense Forces Environmental in life is associated with raised hearing thresholds. The Improvements Association (DFEIA), Tokyo, Japan, 2003, authors' concluded that "this study has found no evidence that 47 pp. RAF personnel who have lived on or near fast jet stations while very young display raised hearing threshold levels The Japan Defense Facilities Environment Improvement associated with noise-induced hearing loss." Association initiated this study in 2003 to provide information on the effects of aircraft overflight noise on communities, Passchier-Vermeer, W., Noise and Health of Children, TNO based mainly on research conducted in the United States and Prevention and Health Report, Netherlands Organization Europe. The document contains the Final Report on this for Applied Scientific Research, Leiden, the Netherlands, project and has two major sections addressing sleep distur- 2000, pp. 52. bance resulting from aircraft noise exposure and hearing loss owing to aircraft noise exposure. In the study, the authors This report gives an overview of the adverse effects of noise provide detailed reviews and annotations for 22 recent relevant exposure on the health of children and covers a broad range studies. In terms of hearing loss, the study concludes that there of topics, including hearing impairment. The author consid- is no evidence of raised threshold shifts in populations in the ers hearing impairment in the fetus, pre-term and full-term vicinity of civil or military airports. babies, pre-school and school children, and teenagers. The studies are not limited to aircraft or environmental noise but International Standards, "Acoustics--Determination of all noise sources. Occupational noise exposure was the only Occupational Noise Exposure and Estimation of Noise- risk factor identified for the fetus, although high levels of Induced Hearing Impairment," ISO 1999, 2nd. ed., 1990- noise in the neonatal intensive care unit and incubator noise 01-15 (E), 17 pp. was identified as the major risk factor for pre-term babies. With respect to pre-school and school-age children, the This International Standard presents, in statistical terms, the author concluded that "The investigations undertaken so far relationship between noise exposure and the "noise-induced show that environmental noise exposure does not have an permanent threshold shift" in people of various ages. It effect on hearing threshold levels of children, with the provides procedures for estimating the hearing impairment exception of exposure to noise from extremely low flying resulting from noise exposure of populations free from auditory military aircraft." With respect to teenagers, the author

OCR for page 30
39 concluded that firecrackers, tractors, snowmobiles, hunting In his seminal article, Schultz (1978) reviewed the data equipment, power tools, musical instruments, portable music from social surveys concerning the noise of aircraft, street players, boom-cars, night clubs, rock concerts, motorcycles, and expressway traffic, and railroads. Returning to the origi- and occupational or technical schools are the main risk nal published data, the various survey noise ratings were factors for hearing loss in teenagers. Environmental noise translated to DNL, and where a choice was needed, an inde- was not considered a risk factor for teenage hearing loss. pendent judgment was made as to which respondents should be counted as "highly annoyed." According to Schultz, ". . . Sixsmith, K. and P. Wheeler, "Auditory Impact of Aircraft the basic rule adopted was to count as `highly annoyed' the Noise on Civilian Populations: Examination of the Scien- people who responded on the upper 27%29% of the annoy- tific Literature for Evidence," Presented at the Inter-Noise ance scale. . . ." (Schultz 1978). The results of 11 of the Symposium, Fort Lauderdale, Fla., Dec. 68, 1999. reviewed surveys showed a remarkable consistency--the so-called "clustering surveys." In performing his analysis, This review examines the scientific literature for any evidence Schultz used a third-order polynomial function to fit the 161 that jet aircraft noise may be associated with hearing impair- data points contained in the 11 "clustering" surveys. ment in populations surrounding civil and military airfields, as measured at frequencies up to 8 kHz. Papers were found For decades, environmental planners have relied heavily using MEDLINE and by searching recent international con- on the Schultz curve for predicting community annoyance ference proceedings. The study includes a review of nine from transportation noise sources. Notwithstanding the studies done in the vicinity of seven civil or military airports methodological questions, errors in measurement of both and two laboratory studies. The studies reviewed included noise exposure and reported annoyance, data interpretation noise levels as high as 130 dBA (Lmax) and 95 dB WECPNL differences, and the problem of community response bias, (~82 DNL). "The laboratory studies suggest that permanent Schultz's recommended relationship has historically been threshold shifts are unlikely to be induced by exposures to air- the most widely accepted interpretation of the social survey craft noise thought to be typical of real life." The authors sum- literature on transportation noise-induced annoyance. marized the results: "In the main, these studies have been con- ducted where environmental noise does not appear to Beginning with the 1978 publication of Schultz's original approach recognized occupational noise limits. Further, it exposure-response curve, work has continued in many coun- may be that the intermittency of environmental noise may tries to conduct field studies, to develop databases with the itself protect hearing from damage." results of new social surveys, and to explore whether separate curves are needed to describe community responses to aircraft, CHAPTER THREE: ANNOYANCE street traffic, and railway noise. The conclusions of several AND AVIATION NOISE major meta-analyses of these data will be reviewed and possi- ble future directions for this line of research will be discussed. Before addressing recent studies related to exposure-response relationships between transportation noise and community In 1992, Federal Interagency Committee on Noise (FICON) annoyance, a brief historical overview is warranted. With the reported that there were no new descriptors or metrics of suffi- development of jet aircraft technology in the early 1950s, cient scientific standing to substitute for the present DNL concern about exposure to noise from transportation sources cumulative noise exposure metric (Federal Agency Review . . . led to the publication of the initial scientific studies of aircraft 1992). The dose-response relationship, as represented by DNL, noise exposure and the responses of communities in the and the percentage of "highly annoyed" remains the best vicinity of airports and, later, for road traffic and railway available approach for analyzing overall health and welfare noise. The concept of "community annoyance" was de- affects for the vast majority of transportation noise analyses. veloped to provide one comprehensive term to describe the overall community response to noise, including both degra- Fidell et al. (1991) were commissioned by the U.S. Air dation of outdoor activities and interference with indoor Force to update this important curve. That update, along with activities. There are two general assumptions: (1) that the the Schultz curve, is the basis of the FICON recommendation noise exposures of interest for policy-making purposes occur and the basis for most U.S. policy on aviation noise. The result over a period of at least a month, and (2) that the population of this major database update was the inclusion of 292 addi- has had between 2 and 6 months to habituate to major changes tional data points to the original 161 data points for a new total in their community-wide noise exposure. Community an- of 453 data points. The result nearly tripled the size of the data- noyance is therefore the aggregate community response to base for predicting annoyance owing to general transportation long-term, steady-state exposure conditions. However, to noise exposure as compared with the original Schultz Curve. adequately support government noise policy-making efforts, As shown in Figure A2, even though the data points nearly it is necessary to synthesize the large amount of data con- tripled, the 1978 relationship still provides a reasonable fit tained in journal articles and technical reports to develop a to the data. Although the article published the widely used useful exposure-response relationship. Statistical data meta- "updated Schultz curve," it also carefully showed the in- analysis techniques are used to accomplish this. dividual data points that went into the synthesis of the curve

OCR for page 30
40 author raises questions about the use of the synthesis data to develop the commonly used annoyance/DNL dose-response relationship. The report arrives at several conclusions, in- cluding "the curve is NOT a measurement of the relationship between DNL and the percentage of the population that would describe themselves as `highly annoyed' and if it is necessary to estimate the dose/response relationship . . . a single constit- uent survey provides a better estimate" (Fields 1994). The Fidell et al. (1991) expansion of the existing commu- nity annoyance research database and their revised predic- tion curve provided a considerable extension of the original Schultz meta-analysis. However, because there were several debatable methodological issues involved in this update, Finegold et al. (1994) reanalyzed the Fidell et al. data and FIGURE A2 Prediction curve from Fidell compared with published the results of this additional meta-analysis. Their original Schultz Curve (adapted from Fidell et al. 1991). re-analysis focused primarily on the choice of screening cri- teria for the selection of which studies to include in the final (see Figure A3; the percentage of "highly annoyed" ranges database and the choice of a data fitting algorithm. Use of from about 5% to more than 70% at 65 DNL). In later years, more stringent study selection criteria resulted in a 12% loss the primary author criticized the use of this simplistic curve, of the original data points. in light of the high data variability, the effect of low- and high- noise exposure levels on the curve fit, and the lack of consid- Using the new data set, a new logistic fit curve as the eration of other variables in community response to noise. prediction curve of choice was developed and adopted by FICON in 1992 for use by federal agencies in aircraft noise- A comprehensive review and critique of Fidell et al.'s up- related environmental impact analyses. It was also adopted date (1991) was later published by Fields (1994), where the as part of the ANSI Standard on community responses to FIGURE A3 All 453 datapoints used in updated dose-response curve (adapted from Fidell et al. 1991).

OCR for page 30
41 relationship between the various transportation noise sources and community annoyance. The European Union position on annoyance is based on its report in 2002 that recommends that the percentage of persons "annoyed" or percentage of persons "highly annoyed" be used as the descriptor for noise annoyance. Similar to Miedema and Vos, the position paper distinguishes between aircraft, road, and rail traffic noise; recommends use of a separate pair of curves ("annoyed" and "highly annoyed") for each; and clearly shows a tendency to treat aircraft, road, and rail noise as unique when estimating the percentage of the population who will be "annoyed" or "highly annoyed" by noise. FIGURE A4 Community annoyance prediction curve Miedema and Vos (1999) further studied the effects of (Finegold et al. 1994). demographic variables (e.g., sex, age, education level, occupational status, size of household, dependency on the noise source, and use of the noise source) and two attitudi- environmental noises. Figure A4 presents the Finegold et al. nal variables (noise sensitivity and fear of the noise source) (1994) curve, which shows that if the data are broken down on annoyance. The results are very interesting and suggest into separate curves for various types of transportation noises that fear and noise sensitivity have a large impact on annoy- (aircraft, roadway, rail noise), aircraft noise appears to be ance. Additionally, Fidell et al. (2002) suggest that a good more annoying at the same DNL than either road or rail noise part of the excess annoyance is attributable to the net influ- (see Figure A5). ence of non-acoustic factors. "A disproportionately large and long-term increase was observed in the prevalence of Over the past decade, Miedema and Vos (1998, 1999) have self-reported high annoyance long after a step increase in compiled the most comprehensive database of community aircraft noise exposure . . . The greater than predicted in- annoyance data yet available, and several studies have been crease in the prevalence of annoyance cannot be attributed published on the results of their meta-analyses. It is a to changes in noise exposure alone" (Fidell et al. 2002). comprehensive review of an issue that has been contentious ever since Schultz published his data in 1978. Separate, non- Some of the most interesting research comes from Fidell in identical curves were found for aircraft, road traffic, and rail- two papers. In "The Shultz Curve 25 Years Later: A Research way noise. Aircraft is shown to be more annoying than road Perspective," he argues that although federal adoption of an or rail noise. Miedema and Vos used three different curves to annoyance-based rationale for regulatory policy has made this describe the data for the three noise categories--aircraft, road approach a familiar one, it is only one of several historical traffic, and railway noise, as shown in Figure A6. However, perspectives, and not necessarily the most useful for all no data were found describing the statistical significance of purposes (Fidell 2003). This tutorial article traces the devel- these differences. One should exercise caution in drawing opment of the dosage-effect relationship on which FICON firm conclusions about the state of knowledge concerning the currently relies, and identifies areas in which advances in genuine understanding might lead to improved means for predicting community response to transportation noise. It provides an important summary of how the annoyance synthesis was developed and the inherent weakness of the DNL/dose-response relationship. In summary, Fidell is highly critical of U.S. policy that relies solely on the synthe- sized dose-response relationship. In the second paper, Fidell and Silvati identified shortcom- ings of a fitting function endorsed by FICON for predicting prevalence rates of annoyance in populations exposed to aircraft noise that are well-understood and well-documented (Fidell and Silvati 2004). The authors argue that the U.S. National Environmental Policy Act (NEPA) requires the use of best-available technology for disclosure of noise impacts of major federal actions; however, the authors' underlying FIGURE A5 Curves for three transportation noise concern is that the reliance on the FICON curve for meet- sources (Finegold et al. 1994). ing NEPA requirements does not use the best available

OCR for page 30
80 If noise exposure decreased property value, one could airport/community environments, market conditions, and have reasonably presumed that the second group was demand variables involved. Although most studies concluded compensated for the existing noise exposure once they will- that aviation noise effects on property value range from some ingly purchased properties that sold at a market-discounted negative impacts to significant negative impacts, some studies price. This has led to the description of aircraft noise as a combined airport noise and proximity and concluded that the one-time effect on property value. Prospective homebuyers net effect on property value was positive. Prospective home- that lacked information about the noise characteristics of buyers were at times not well-informed about the noise levels noise-impacted properties "handicaps the operations of the of aircraft operations near the property of interest. Lacking real estate market, results in disappointment for some buyers, information often led to high bid prices and possible disap- and serves to exacerbate conflict between homeowners and pointment after purchase. Homeowners that experienced an the airport authority" (Frankel 1991). increase in noise levels bear the burden of aviation noise. However, once noise levels stabilized, the next homeowner A study conducted around Manchester Airport, England, was compensated once the property value adjusted owing to showed that when using the Noise and Number Index mea- the effects of noise. Lastly, the technology available to analyze sure (previous official index of aircraft noise in England; the data has improved throughout the years. The spatial nature of Noise and Number Index is similar to the DNL metric but aircraft operations, noise contours, and property location will uses perceived noisiness curves, not perceived loudness continue to prompt studies founded in GIS analysis that will curves) results revealed no significant negative relationship improve our understanding of the effects of aviation noise on between noise and property value (Tomkins et al. 1998). property value. However, a significant negative relationship between noise and Annotated Bibliography--Aviation Noise Effects dwelling price is detected when the Leq measure is substituted . . . on Property Values A possible conclusion might therefore be that, although it defines a smaller core of properties affected by noise, Leq nevertheless displays greater accuracy in identifying those which are truly Bell, R., "The Impact of Airport Noise on Residential noise-blighted. Real Estate," The Appraisal Journal, Vol. 69, No. 3, July 2001, pp. 312321. Proximity to the airport also had significant impacts, but at a decreasing rate. Hence, "noise nuisance and distance have quite The author's discussion on this topic was very succinct and in- distinct and opposite effects upon property prices" (Tomkins et formative. From the perspective of a real estate professional, al. 1998). The net impact was that property location in close noise was classified as a Detrimental Condition that was im- proximity to the airport was a more important factor of property posed on homeowners on a permanent basis. The document value than noise. The study interestingly concluded: presented no further original research, but referenced several well-known sources and study results. Additionally, the author that not all property prices are higher than they would otherwise outlined the measurement of noise, presented some of the be in the absence of the airport. Much depends upon the particular health effects of airport noise, and concluded that as popula- configuration of noise and proximity characteristics and thus some households are net gainers whilst others are net losers in terms of tion and airports expand, defining property valuation will property values. Households which benefit the most are those liv- challenge the real estate analyst. This document did not ing near to the airport, but whose location in relation to the flight include an original Noise Depreciation Index per decibel. path places them on a relatively low-level noise contour. House- holds which suffer the most are those at some distance from the airport but which nevertheless are exposed to higher noise levels. Cohen, J.P. and C.C. Coughlin, Spatial Hedonic Models of Airport Noise, Proximity, and Housing Prices, Federal Re- Lastly, studies showed buyer demand was an important serve Bank of St. Louis, Sep. 2006, 27 pp. component in the real estate market. A buyer's demand or will- ingness to pay guided the seller's asking price. Unfortunately Despite the refrain that housing prices are determined by "lo- for researchers, determining a buyer's demand was highly cation, location, and location," no prior studies of airport noise complex owing to extensive decision-making variables, not and housing prices have incorporated spatial econometric the least of which was the buyer's perception of noise. On one techniques. The authors compare various spatial econometric hand, some buyers "will not purchase a property at any cost models and hedonic models (methods of estimating demand or that is by a detrimental condition. [On the other hand] a por- pricing) to examine the impact of noise on 2003 housing val- tion of the population seems more or less imperturbable" by ues near HartsfieldJackson Atlanta International Airport. the effects of noise (Bell 2001). Spatial effects are best captured by a model including both spa- tial autocorrelation and autoregressive parameters estimated by a generalized-moments approach. The inclusion of spatial Summary effects magnifies the negative price impacts of airport noise. Finally, after controlling for noise, houses farther from the air- The studies of the effects of aviation noise on property values port tend to sell for less, implying that airport proximity is an are highly complex owing to the differences in methodologies, amenity. This paper included highly technical descriptions of

OCR for page 30
81 the spatial models and techniques used and included very At higher noise levels, the survey results were much higher useful references from several, at times, contrasting refer- than the hedonic study. The author concluded that a buyer was ences. This document did not include an NDI per decibel, but compensated for the purchase of a home within areas affected did include a noise discount in the 65 dB and 70 dB DNL by airport noise once market-discounting forces reduced the contours for the log, semi-log, and linear specification. price of the home. This document did not include an NDI per decibel, but reported property discounts at four different noise Desai, V. and J. Chen, "The Impact of Airport Noise on levels ranging from 62.5 dB to 77.5 db DNL. Housing Values: A Summary Report," FAA, Office of Environment and Energy, Washington, D.C., Sep. 1994. Gillen, D., The Role of Noise Valuation in Assessing Infra- structure Investment and Management: A Case Study of Pear- This report presents a summary of an analytical approach son International Airport, IV Ibero-American Congress on designed to estimate the effect of airport noise on housing Environmental Acoustics, Sep. 1417, 2004, 33 pp. values. The report describes a procedure that consists of three steps: (1) identification (by a local realtor) of two neighbor- This paper examined the modeling that was undertaken to es- hoods that have similar characteristics except for noise tablish both a value for noise or quiet as well as a measure of levels, (2) selection of a sample of houses from each neigh- the economic costs of a runway expansion project at Pearson borhood with reasonably similar individual housing charac- International Airport. The valuation was based on the use of teristics, and (3) use of a modified appraisal process (by a the hedonic model. The valuations were a key input in the local appraiser) and statistical modeling to compare the hous- benefit-cost analysis of the runway expansion, which was ing values in the two neighborhoods. The results of the stud- one component of the environmental assessment of the ies indicate that the neighborhood pair model is viable and project. The author described in detail the quantification of helps establish the boundaries of the effect that airport noise changes to noise exposure by measuring the existing home- has on housing values at a given airport. The report owners' enjoyment levels, transaction costs of moving, cost concludes that "the magnitude of this impact cannot be of lost utility by those who move, and increased nuisance estimated at the national level at this time, since the results noise and reduction in services from the homes of those who varied across a wide range for the airports studied, and only choose not to move. "The magnitude will depend on a num- a small sample of airports was considered." The primary ber of factors including sensitivity to noise and activities that objective of these studies was not to examine the issue of are perceived affected by noise such as sleep, reaction, or airport noise impact in detail at the local level, but to assess solitude." The paper also examined the difference in noise the feasibility of a method to examine the effect of airport depreciation between condominiums and single or semi- noise on property values. The studies indicate that the detached homes. Results showed that the NDI for condo- methodology is viable and reasonably economical, and there miniums was less than half that for single or semi-detached are several approaches that may be used to implement this technique for a nationwide examination. homes. Therefore, the author concluded that condominiums were less affected by airport noise. FAA Airport Benefit-Cost Analysis Guidance, Federal Avi- ation Administration, Washington, D.C., Dec. 15, 1999. Judd, G.D. and D.T. Winkler, "The Impact of an Air Cargo Hub on Property Values," Presented at the Ameri- The document includes guidance to use the INM to identify can Real Estate Society 2000 Conference, Santa Barbara, a noise benefit in terms of a reduction in the non-compatible Calif., Mar. 29Apr. 1, 2000, 7 pp. land-use area, and costs in terms of an increase in the noise non-compatible land-use area. However, there was no further This paper examined the impact on property values after a guidance to quantify noise benefits and costs. This document public announcement regarding the start of hub operations by did not include an NDI. a major U.S. cargo airline at the PiedmontTriad Airport. Airport expansion and associated growth bring about Frankel, M., "Aircraft Noise and Residential Property increased income and employment, and proximity to the Values: Results of a Survey Study," The Appraisal Journal, PiedmontTriad Airport is an amenity associated with loca- Jan. 1991, pp. 96108. tion. For residential properties, however, airport proximity may have negative effects on home prices because of in- This study included the results of two surveys of realtors creases in noise, traffic congestion, and perceived crash po- and appraisers in 35 suburban communities near Chicago's tential. By the use of a hedonic model, the authors attempted O'Hare International Airport who were knowledgeable about to measure the impact of an announcement of an increase in real estate markets and property transactions. The author ad- noise. Because there was no change in actual aircraft opera- dressed the home-buying process from the perspective of the tions at the time of this study, the impacts of a change in noise real estate professional and compared the survey results with a levels was not calculated. Although the announcement previous hedonic study done by Nelson (2004). The survey brought on much debate, "results of the research reveal that noise discount results were fairly similar until the 68 dB DNL. residential property values and associated volumes of sales in

OCR for page 30
82 close proximity to the airport were unaffected by the hub noise exposure levels of 75 dB or less, whereas in Canada the announcement, while housing more distant from the airport discount was 0.8% to 0.9% per decibel. experienced an increase in value." This document did not include an NDI. Salvi, M., Spatial Estimation of the Impact of Airport Noise on Residential Housing Prices, Zurcher Kantonalbank, Lipscomb, C., "Small Cities Matter, Too: The Impacts of Zurich, and cole Polytechnique Federale, Lausanne, an Airport and Local Infrastructure on Housing Prices in Switzerland, 2007, 20 pp. a Small Urban City," Review of Urban and Regional Devel- opment Studies, Vol. 15, No. 3, Nov. 2003, pp. 255273. This paper applied spatial econometric techniques to mea- sure the impact of airport noise on the price of single-family According to the author, small cities with a relatively smaller homes in the Zurich airport area. A hedonic model was spec- number of amenities and features tend to have fewer num- ified with a spatial error component accounting for local spa- bers of variables that operate to determine house prices. tial dependence. The estimation technique was based on the Therefore, hedonic prices could be estimated adequately generalized moment estimator. The analysis concluded that for a single neighborhood in a small city with publicly there was a significant non-linear impact of airport noise on available data, particularly for local officials who do not housing prices. For moderate noise levels of 55 dB Leq, de- have the time or financial resources to complete detailed preciations amount to 2.4% of the transaction price, increas- studies of their cities. In this study, a general model was ing non-linearly to 27.2% for noise levels around 68 dB Leq. estimated that uncovered the impacts of airport-related noise, local recreational amenities, public transportation Tomkins, J., N. Topham, J. Twomey, and R. Ward, services, and schools on housing prices in the city of Col- "Noise Versus Access: The Impact of an Airport in an lege Park, Georgia. A unique condition that may have Urban Property Market," Urban Studies, Vol. 35, No. 2, biased the results whereas "[the city] houses a high percent- 1998, pp. 243258. age of Hartsfield International Airport employees . . . Higher [property] sales prices due to being closer to the airport This paper addressed the general question of whether the suggests that the benefits of being near a large air transpor- costs to those within airport proximity outweigh the bene- tation hub outweigh the liabilities." The study showed that fits of access, employment, and improved infrastructure. neighborhood amenities affected property value as well. The Noise impact areas were based in the Noise and Number author concludes, Index. Based on data relating to Manchester airport and its surrounding areas, the approach by the authors involved an For planners and economic developers in other small urban cities investigation of the extent to which such proximity effects interested in revitalizing neighborhoods and increasing property were capitalized into residential property prices. The values, these results suggest that playgrounds, parks, and other results provided some evidence to suggest that circum- recreational infrastructure (tennis court, basketball courts, etc.) can be used as economic development tools to revitalize neigh- stances may exist where positive attributes, such as borhoods with low property values. improved access and employment opportunities, may be more highly valued by local residents than the negative This document did not include an NDI, but listed price externality effects of airport proximity. The authors con- fluctuation for airport proximity and for local amenities. cluded that properties that are close to the airport, but within a low-noise level area, received the most benefits of Nelson, J.P., "Meta-Analysis of Airport Noise and He- proximity. donic Property Values: Problems and Prospects," Journal of Transportation Economics and Policy, Vol. 38, No. 1, Uyeno, D., S.W. Hamilton, and A.J.G. Biggs, "Density of Jan. 2004, 27 pp. Residential Land Use and the Impact of Airport Noise," The Journal of Transport Economics and Policy, Vol. 27, Twenty hedonic property value studies were analyzed, cover- No. 1, Jan. 1993, pp. 318. ing 33 estimates of the noise discount for 23 airports in Canada and the United States. Meta-analysis was applied to the nega- The study estimated the impact of airport noise on property tive relationship between airport noise exposure and residen- values for detached houses near Vancouver International tial property values. About one-third of the estimates have not Airport and, for the first time in the literature, for multiple- been previously reported in the literature or were not included unit residential condominiums (buildings with many individ- in previous meta-analysis. The weighted-mean NDI or noise ually owned units, either owner-occupied or rented by that discount is 0.58% per decibel. A meta-regression analysis ex- owner to another party) and for vacant land. The hedonic amined the variability in the noise discounts that might be the models used assigned different amenity variables to single- result of country, year, sample size, model specification, mean family homes, condominiums, and vacant land that resulted property value, data aggregation, or accessibility to airport em- in NDI values of 0.65%, 0.90%, and 1.7%, respectively. ployment and travel opportunities. The cumulative NDI in the Contrary to other studies, this study showed that condomini- United States was approximately 0.5% to 0.6% per decibel at ums had a higher NDI than single-family homes.

OCR for page 30
83 CHAPTER ELEVEN: EFFECT OF METEOROLOGY One of the consequences of the complex way weather ON AVIATION NOISE affects sound propagation is that noise models are limited to estimating noise levels for average conditions. For any Meteorology plays a very important role in the propagation given flyover the noise experienced at an observer location of sound. Temperature and/or wind gradients cause refrac- is the product of the aircraft noise level and the effect of the tion (bending) of sound waves. Air absorbs sound; therefore, atmosphere on sound propagation. Comparing noise model as sound travels through the atmosphere it is attenuated by predictions with short-term noise measurements is mean- this absorption. Complicating matters is that air absorption ingless, because atmospheric effects are not adequately varies with temperature and humidity and the frequency of accounted for in the model. However, long-term measure- the sound. For example, sound is absorbed much better in ments will produce an average noise level in which atmo- hot, dry conditions than cold, dry conditions. Figure A13 spheric effects will tend to average out and comparison with plots sound absorption as a function of temperature and hu- noise model results will be much more meaningful. This midity. The absorption effect is a smaller effect than refrac- caution should be noted for any short-term measurement tion effects. In the real atmosphere the temperature, humid- program. ity, and wind speed and direction are not homogeneous, but are changing constantly. Summary If the atmosphere were homogeneous, the task of describ- As evidenced by even a generalized discussion of aviation ing sound propagation would be relatively simple. Under nor- noise effects by meteorology, this field of study is incredibly mal atmospheric conditions, temperature decreases with technically detailed and complex. Most new research altitude (adiabatic lapse rate). The resulting effect on sound published discussing these effects are not for the average waves is that sound waves are bent upward. When tempera- reader. However, a very brief and minimally complex sum- ture increases with altitude, it is called a temperature inver- mary is provided here. sion, and temperature inversions are common at night. Tem- perature inversions cause sound waves to bend downward. It Gabrielson's (2006) "Refraction of Sound in the Atmo- was keenly observed during the Civil War and World War I sphere," is an excellent history of sound propagation through that cannon fire and bomb blasts were sometimes heard at atmosphere from the 1700s to date. It should be mandatory very great distances from the battlefield, although not audible reading for anyone seeking to understand the propagation of at much nearer distances. This phenomenon could not be ex- sound through the atmosphere, and how weather affects that plained by air absorption leading to refraction or bending of propagation. For example, he notes a school of thought dur- sound waves. Wind gradients can produce a similar effect at ing the Civil War and World War I that provided evidence of low wind speeds. A wind gradient results when wind speeds refraction through the observation of battle cannons or bomb near the ground are slower than wind speeds at increasing al- blast sound at long distances that were not heard at short dis- titudes. This gradient causes refraction of sound waves in the tances. Recorded observations proved beyond a doubt that same way that temperature gradients do. At high wind speeds refraction of sound in the atmosphere caused sound to be in- turbulence creates a very complex mixing effect. audible in some areas and clearly audible in others, com- pletely independent of the effects of distance. Gabrielson's A schematic diagram of the effects of weather on sound publication is a fabulous history of atmospheric influences on propagation is shown in Figure A14. The INM includes the sound. effect of meteorology in two ways: First, temperature is used to calculate aircraft performance; that is, an aircraft climbs Several publications are extraordinarily complex, such as much better in cool weather than hot weather. The option to Hallberg et al.'s (1985) report describing the problem's com- match atmospheric sound propagation to aircraft perfor- plexity and some of the physics of the problem. Results indi- mance was added to INM Version 6.0. The INM uses noise cate that sound level increases as the curvature goes from neg- data in the form of NPD curves. These data come from air- ative to positive values. Comparisons with other investigations craft certification data that are corrected to a standard tem- agreed. However, calculations of acoustic theory results perature and humidity. The NPD curves in the INM are at the showed large discrepancies with those measured. Five years standard temperature and humidity. INM Version 7 includes later, in 1990, NASA's Fourth International Symposium on options to adjust the NPD curves to the user-selected average Long-Range Sound Propagation included 22 technical papers temperature and humidity (INM Users Guide 2007). For tem- that, while scientific in nature, are presented in three broad peratures near standard conditions or at distances near the sections: ground effects on propagation, infrasound (very low airport, this adjustment is small; however, at large propaga- frequency) propagation, and meteorological effects on sound tion distances or non-standard conditions the effects are non- propagation. trivial. Even this correction is somewhat simplistic, in that it is based on a homogeneous atmosphere; that is, constant tem- In 1994, Wilson and Thomson's report discussed the effects perature and humidity. It does not attempt to correct for tem- of atmospheric wind and temperature fluctuations on acoustic perature gradients. signal variability, with emphasis on large-scale turbulence.

OCR for page 30
84 FIGURE A13 Atmospheric sound absorption as a function of temperature and humidity (Beranek, Noise and Vibration, McGraw-Hill 1981).

OCR for page 30
85 FIGURE A14 Effects of weather on sound propagation (Mestre Greve Associates 2007). Although very technically complex, the article shows how sim- (2007) description of how sound propagation through a for- plistic assumptions of atmospheric homogeneity may result in est is affected by the microclimate of the canopy, scattering significant differences to real-world conditions. by trunks and stems, and ground reflection. Each of these effects is such a strong contributor to the attenuation of The Report on Standard Method of Computing Noise sound that mutual interactions between the phenomena Contours Around Civil Airports (2005), commonly referred could become important. Results indicate high frequency to as Doc. 29, is analogous to SEA AIR 1845, which is the attenuation owing to the forest that increases with distance. technical basis for computations contained in the INM. The article captures the complexity of the problem and iden- Appendix D of Doc. 29 outlines temperature and humidity tifies model techniques for this particular application, but corrections that may be needed in the acoustic model por- does not provide a general solution useable in today's tion of a noise model such as INM, which use noise data in aircraft noise models. the form of NPD curves. In the INM, the NPD are at stan- dard temperature and humidity. Doc. 29 provides technical routines to adjust the NPD to actual standard conditions of Annotated Bibliography--Effect of Meteorology temperature and humidity. It does not attempt to correct for on Aviation Noise temperature gradients, however. Embleton, T., "Tutorial on Sound Propagation Out- Another technical article describing atmospheric experi- doors," The Journal of the Acoustical Society of America, ments of sound propagation is Swearingen and White's Vol. 100, No. 1, July 1996, pp. 3148.

OCR for page 30
86 This tutorial is a comprehensive guide to the propagation of great distance were needed. Interestingly, the prevailing be- sound outdoors, and provides a history of propagation theo- lief was that sound traveled poorly through fog (and rain and ries and description of the physical properties involved. In snow). However, sound does penetrate fog, "but the con- addition to the narrative description of the physics involved, trary belief had become the `expert opinion' from the early technical details are provided. The tutorial emphasizes field 17th well into the 19th century." Curious observations con- measurements and physical interpretations. founded the best expert opinions. Sound traveled better with the wind than against the wind; houses and hills did not al- European Civil Aviation Conference, Report on Standard ways block sound, and distant sound appeared clearer and Method of Computing Noise Contours Around Civil Air- louder at night. Another curious observation that ultimately ports, Doc. 29, Ed. 3, Vol. 2, 2005, 126 pp. led to experiments proving the refraction, or bending, of sound waves was the observation that during battle cannon This document, commonly referred to as Doc. 29, is analo- blasts were often heard from very long distances away, gous to SAE AIR 1845, which is the technical basis for the although not heard at closer locations. Such observations computations contained in the INM. Doc. 29 includes were common during the Civil War. The history of the de- Appendix D, which outlines the temperature and humidity velopment of this science by such pioneers as Stokes, corrections that may be needed in the acoustic model portion Reynolds, and Schrodinger, and the use of kites to measure of a noise model such as INM. INM has historically used temperature gradients in the atmosphere are included in this temperature to account for the change in aircraft perfor- interesting and well laid out paper. World War I provided mance that results from a change in air density. As the more evidence of refraction through observation of bomb temperature increases the air gets thinner, and an aircraft blast sound at long distances that were not heard at short does not perform as well as it does at lower temperatures. distances. Remember that observation of bomb blast noise The noise models use noise data in the form of NPD curves. was a key early warning signal. After the war a series of ex- These are curves of noise level versus distance, with sepa- periments were set up in which bomb blasts were witnessed rate curves for each power setting. These curves are derived by observers located throughout Europe The recorded from aircraft certification data. Aircraft certification data are observations proved beyond a doubt that refraction of sound collected within a specified range of temperature, humidity, in the atmosphere, the bending of the sound waves with tem- and wind conditions and corrected to a standard temperature perature and wind gradients, caused sound to be inaudible and humidity. The NPD curves in the INM are at the stan- in some areas and clearly audible in others, completely dard temperature and humidity. Doc. 29 provides technical independent of the effects of distance. This article is manda- routines to adjust the NPD curves to the actual temperature tory reading for anyone seeking to understand the propaga- and humidity from standard conditions. For temperatures tion of sound through the atmosphere and how weather near standard conditions or at distances near the airport, this affects that propagation. adjustment is small. However, at large propagation dis- tances the effects are non-trivial. INM Version 7 contains Hallberg, B., C. Larsson, and S. Israelsson, "Measure- the ability to provide this temperature and humidity correc- ments of Meteorological Effects of Long-Range Sound tion to the acoustic model. Even this correction is somewhat Propagation Using m-sequence Correlation," The Journal simplistic, in that it is based on a homogeneous atmosphere; of the Acoustical Society of America, Vol. 78, No. 3, Sep. that is, constant temperature and humidity. It does not 1985, pp. 10381044. attempt to correct for refractions. This is a very technical article that is not for every reader. Gabrielson, T.B., "Refraction of Sound in the Atmosphere," However, the introduction and first section do a good job of Acoustics Today, Apr. 2006, pp. 716. outlining the complexity and some of the physics of the problem. A correlation method was used for measuring This article presents an excellent history of the evolution of sound levels 1 km away from a point source 1.25 m above thinking about sound propagation through the atmosphere. the ground, a crop field and a snow-covered ground, re- The author begins by pointing out how natural it is to think spectively. Meteorological parameters were monitored si- that sound travels more or less in a straight line. For the most multaneously. Wind speed and temperature were measured part, when you hear a sound you know where to look. As the at several elevations, together with wind direction, relative science of sound developed in the 18th and 19th centuries humidity, and atmospheric pressure at a single height. The there was great misunderstanding about sound propagation. effect of refraction on the sound level variation is inter- Early theories on sound propagation focused solely on preted in terms of the curvature for near-horizontal sound absorption of sound by air and that absorption varied with rays. It is found that the sound level increases as the curva- temperature, humidity, and the frequency of the sound. The ture goes from negative to positive values. Comparisons need for understanding sound propagation was acute, with with other investigations were made, and qualitative agree- hundreds of ships being wrecked in thick coastal fogs. ment is found. Calculations with acoustic theory were Because lighthouses were of little use in this weather, more made, the results of which show large discrepancies with powerful sound signals able to give warning and guidance at those measured.

OCR for page 30
87 National Aeronautics and Space Administration, research in the atmospheric sciences literature regarding "Fourth International Symposium on Long-Range length scales and anisotropy is reviewed and incorporated into Sound Propagation," Proceedings of a Symposium Spon- an acoustic propagation model. An important conclusion is sored by NASA, the University of Mississippi, and the that large-scale turbulence is a significant cause of acoustic Open University of England, Langley Research Center, signal fluctuations, particularly in the signal phase. This is im- May 1990, 282 pp. portant to realize when comparing noise measurement results with noise model results. Noise models produce an estimate This symposium included 22 technical papers by scientists of an average over time, although noise measurement results studying long-range propagation of sound. The papers are very may differ significantly for a given single event. technical and presented in three broad sections: ground effects on propagation, infrasound (very-low frequency) propagation, CHAPTER TWELVE: EFFECT OF TOPOGRAPHY and meteorological effects on sound propagation. A reader AND GROUND ABSORPTION seeking technical and mathematical descriptions of long-range ON AVIATION NOISE sound propagation will find the symposium proceedings useful. It is not for the lay non-technical reader. Aircraft sound heard by an observer can be influenced by a number of factors. In the previous chapter, the effect of Swearingen, M.E. and M.J. White, "Influence of Scatter- meteorology was one such factor. In this chapter, the propa- ing, Atmospheric Refraction, and Ground Effect on gation of sound over the ground and how sound is affected by Sound Propagation Through a Pine Forest," The Journal terrain is discussed. This is a highly complex and technical of the Acoustical Society of America, Vol. 122, No. 1, July topic and only a simplified description of shielding and 2007, pp. 113119. ground effects is presented in this synthesis. When an aircraft is directly overhead, the sound experienced by an observer is This is a very technical article that describes experiments of only affected by meteorology. However, when the aircraft is sound propagation through a forest, which is affected by the at lower elevation angles the sound experienced by an microclimate in the canopy, scattering by trunks and stems, observer is the sum of the sound that travels in a straight line and ground reflection. Each of these effects is such a strong from the aircraft and the sound reflected off of the ground. contributor to the attenuation of sound that mutual interactions The interaction of sound traveling over the ground is com- between the phenomena could become important. A sound plex. It is often simplified into "soft" and "hard" ground propagation model for use in a forest has been developed that propagation. Sound propagation over water is an example of incorporates scattering from trunks and branches and atmo- hard ground propagation. Water does not absorb sound well, spheric refraction. Comparisons with experimental data are making it a good reflector of sound. The acoustics of sound's made. Cumulative influences of the separate phenomena are interaction with ground are very complex; however, good examined. The method developed in this paper is compared empirical methods are available and incorporated into sound with previously published methods. The overall comparison propagation models. The effect of ground absorption on a with spectral transmission data is good, suggesting that the sound traveling near the ground is addressed by lateral atten- model captures the necessary details. The results show high uation algorithms used in models like the INM and are frequency attenuation owing to the forest that increases with defined by industry standards. In this case the standard is distance. The paper captures the complexity of the problem published by the SAE in AIR 5662 (Method for Predicting and identifies model techniques for this particular application, Lateral Attenuation of Airplane Noise 2006). but does not provide a general solution useable in today's aircraft noise models. Terrain may have two effects on sound propagation. An observer on a hill is higher and closer to an aircraft than if on Wilson, D.K. and D.W. Thomson, "Acoustic Propagation flat terrain. Terrain can also act as a sound barrier. These Through Anisotropic, Surface-Layer Turbulence," The examples are shown schematically in Figure A15. INM Journal of the Acoustical Society of America, Vol. 96, No. includes both effects in computing aircraft noise levels. 2, Aug. 1994, pp. 10801095. The amount of noise reduction that terrain shielding The effects of atmospheric wind and temperature fluctuations provides is critically dependent on the geometry of the on acoustic signal variability are discussed, with emphasis on barrier. Figure A16 shows a schematic diagram of an earthen the effects of large-scale turbulence. This is a very technical berm shielding an aircraft during a ground runup. For the journal article, but it is useful to show that simplistic assump- barrier to be effective it must break the line of sight (solid tions of atmospheric homogeneity may result in significant line) between the observer and the aircraft engines. The differences to real-world conditions. Such large-scale turbu- amount of noise reduction is dependent on how much the line lence is anisotropic (different properties at different loca- of sight is broken and the frequency of the sound. The differ- tions), is generated by both shear and buoyancy instabilities, ence in path length between the line of sight and the path over and has structure that depends strongly on the meteorological the top of the barrier (broken line) is an important factor conditions as well as the distance from the ground. Previous in determining the barrier noise reduction; the higher the

OCR for page 30
88 NOISEMAP is a noise contour prediction model used by the Air Force and other organizations to compute envi- ronmental noise around airbases and airports. Within NOISEMAP, the world is presumed flat and ideal in temper- ature/humidity--flat terrain, no barriers or obstructions to the line of sight between source and receiver, and ideal stan- dardized temperature and humidity. In 1992, Plotkin et al. extended NOISEMAP to account for three-dimensional terrain effects and for the effect of varying ground properties. The report presents detailed descriptions of how the NOISEMAP model would have to be modified to account for topography. Another noise prediction model is the FAA's INM, currently updated in 2007 by means of INM Version 7. INM Versions 6.2 and later had the ability to correct for local topography, slant range distance, and shielding effect for terrain that blocks line of sight between the aircraft and observer. Terrain data may now be imported into INM from FIGURE A15 Schematic of terrain effects (Mestre standard digital terrain sources, or input by the user, which is Greve Associates 2007). fully described in the INM User's Guide (2007). The inclusion of shielding calculations in the INM allows it to barrier, the greater the noise reduction. The barrier will work better at new airports that have hills or steep valleys attenuate high-frequency sound much better than low- nearby. The shielding calculations in INM Version 7 are frequency sound. based on the methodology implemented in FHWA's Traffic Noise Model. Summary In 1994, NATO/CCMS issued a final report from the Although most research related to topography and ground working groups identifying various modeling techniques absorption is highly technical in nature, generalized conclu- used in different countries and describing issues associated sions may be made. Recent research has validated and recal- with modeling topographic effects on aviation noise ibrated various noise prediction models that have increased (NATO/CCMS 1994). Included are the effects of slant range the understanding of sound wave influences. distance and the effects of shielding. The report presents recommendations for including topographic effects in The FHWA's Traffic Noise Model (1998) was prepared aviation modeling. for traffic noise analysis, but includes one of the best descrip- tions of how noise barrier effects on transportation noise can Some of the most provocative new research has been be modeled. It includes detailed methodologies to compute prepared by the Volpe Center at the Massachusetts Institute noise barrier effects created by either natural topography or of Technology. In their May 2000 report, Senzig et al. exam- man-made structures. Although this information has enabled ined the applicability of currently available mathematical the increased sophistication of barrier noise reduction, it re- models of lateral attenuation. Analysis of the data revealed mains fundamental in all topographical analyses. that lateral attenuation is a function of aircraft geometry; FIGURE A16 Example of terrain shielding geometry (Mestre Greve Associates 2007).

OCR for page 30
89 lateral attenuation for aircraft with tail-mounted engines NATO/CCMS Working Group Study, Effects of Topog- generally agreed with published literature, although lateral raphy on Propagation of Noise in the Vicinity of Airfields, attenuation for aircraft with wing-mounted engines were No. 200, June 1994, 44 pp. found to be less than documented in the literature. This lower lateral attenuation calculation results in an underprediction of This volume constitutes the final report of the working group sideline noise in the existing noise prediction models. SAE's that was established as a subgroup to the Pilot Study on AIR 5662 (2006) represents a major reformulation of a 1981 Aircraft Noise under the auspices of NATO's Committee on AIR (AIR 1751), and provides detailed calculation methods the Challenges of Modern Society. The report identifies the to calculate lateral attenuation. It includes the effects of various modeling techniques used in different countries and engine mount position (fuselage versus wing mount). INM describes the issues associated with modeling topographic Version 7 (referenced earlier) includes the methodology effects on aviation noise. Sample calculations and contours specified in AIR 5662 for calculating lateral attenuation. are presented. The report discusses the effect of topography on slant range distance (an observer is closer to an aircraft In summary, both noise prediction models, INM Version when that observer is on a hill) and the effects of shielding 7 and NOISEMAP, are the most commonly used in the resulting from topography. Shielding is not important when United States and much of the world and have been updated aircraft are directly overhead of an observer, but may be very to include algorithms for adjusting lateral attenuation and important when an aircraft is at low elevation angles and a local terrain specifications where needed. hill is between the observer and the aircraft. The report presents recommendations for including topographic effects Annotated Bibliography--Effect of Topography in aviation modeling. and Ground Absorption on Aviation Noise Plotkin, K.J., C.L. Moulton, and E. Stusnick, Feasibility INM User's Guide, Version 7.0, FAA-AEE-07-04, Office of of Incorporation of Terrain Effects into NOISEMAP, Environment and Energy, Federal Aviation Administra- Dayton, Ohio, Oct. 1992, 42 pp. tion, Washington, D.C., Apr. 2007, 446 pp. NOISEMAP is used by the Air Force and other organizations INM includes the ability to correct for local topography. This to compute environmental noise around airbases and includes the effect of topography on slant range distance (the airports. Within NOISEMAP, ground is assumed to be flat distance between the observer and aircraft) when the observer and level, at the same altitude as the airbase and runways. is on higher terrain and thus closer to the aircraft. INM Version The only effect of ground on sound propagation is incorpo- 6.2 and later also includes the ability to calculate shielding rated in a single algorithm representing average attenuation effects for terrain that blocks line of sight between the aircraft of sound at small angles of incidence. In most situations, the and the observer. Terrain data may be imported into INM from "flat earth" and "average ground absorption" assumptions standard digital terrain sources or input by the user. The User's are entirely reasonable. There are, however, situations where Guide provides detailed instructions on how to implement this ground is particularly "hard" or "soft," or where the ground and all the other features of the INM. The inclusion of shield- has significant departures from flat and level. A study has ing calculations in the INM allows the INM to work better near therefore been conducted of the feasibility of extending airports that have hills or steep valleys nearby. NOISEMAP to account for three-dimensional terrain effects and for the effect of varying ground properties. The report Method for Predicting Lateral Attenuation of Airplane presents detailed descriptions of how the NOISEMAP model Noise, SAE AIR 5662, Society of Automotive Engineers would have to be modified to account for topography. (SAE), Washington, D.C., 2006. Senzig, D.A., G.G. Fleming, and J.P. Clarke, Lateral Atten- SAE published this Aerospace Information Report (AIR) in uation of Aircraft Sound Levels over an Acoustically Hard 2006. It represents a major reformulation of a 1981 AIR (AIR Water Surface--Logan Airport Study, Langley Research 1751). Lateral attenuation is very important when an aircraft Center, National Aeronautics and Space Administration, is at a low-elevation angle relative to the observer. Lateral at- Hampton, Va., May 2000, 101 pp. tenuation accounts for the interaction of the sound wave with the ground as the sound propagates near the ground. Even as NASA's Langley Research Center sponsored the Acoustics the elevation angle increases, the ground has a significant Facility at the U.S.DOT's John A. Volpe National Trans- effect on the sound level at the receiver. At high-elevation portation Systems Center and the Massachusetts Institute of angles the effect of the ground attenuation disappears. AIR Technology to conduct a noise measurement study at Logan 5662 provides detailed calculation methods to compute International Airport in Boston, Massachusetts, during the lateral attenuation. It includes the effects of engine mount summer of 1999 to examine the applicability of currently position (fuselage versus wing mount) on lateral attenuation. available mathematical models of lateral attenuation. Analy- INM Version 7 includes the methodology specified in AIR sis of the data collected revealed that lateral attenuation is a 5662 for calculating lateral attenuation. function of aircraft geometry. Lateral attenuation for aircraft

OCR for page 30
90 with tail-mounted engines was found to agree with the a more precise meaning than should be taken from the data. published literature, as well as that included in existing Areas of annoyance that remain to be investigated include the aircraft noise models. Lateral attenuation for aircraft with relationship between single-event noise levels and annoy- wing-mounted engines was found to be less than documented ance. Use of data not previously available, including airport in the literature. This lower lateral attenuation for aircraft noise monitoring systems, flight tracking systems, and with wing-mounted engines results in a general under- geographic information systems, may prove to be a rich prediction of sideline noise in the existing noise models. source of data in understanding annoyance and meteorologi- Measurement sites included effects of over-water sound cal and topographical effects. propagation. Mathematical details of the model of sound propagation over "hard" and "soft" surfaces are provided. Aviation noise effects on schools and school children have been well-researched and documented. Recent studies Traffic Noise Model (FHWA TNM), Version 1.0-- indicate a potential link between aviation noise and both Technical Manual, FHWA-PD-96-010, DOT-VNTSC- reading comprehension and learning motivation, particularly FHWA-98-2, Final Report, Federal Highway Adminis- for those children who are already scholastically challenged. tration, Washington, D.C., Feb. 1998. Other studies indicate increased stress levels for children in high-noise environments. New best practices designs for in- This technical manual describes the FHWA Traffic Noise terior classroom acoustics and speech intelligibility have Model. Although it does not address aircraft noise specifi- been completed, but do not address intermittent noise such as cally, the principals and equations for estimating the shield- aviation noise. Some research has indicated that effects ing effects of a barrier, such as that formed by topographic of aviation noise may differ from the effects of other shielding, are described in detail. It is a useful resource for transportation noises. Speech interference, although quite understanding noise barrier effects. important, has not had the benefit of research as related to intermittent noise sources. CHAPTER THIRTEEN: CONCLUSIONS New definitions and criteria for natural soundscape in na- Nearly every aspect of aviation, and related technology, has tional parks and Native American tribe lands are being es- changed since the 1985 publication of FAA's "Aviation Noise tablished, and new dose-response relationships may be used Effects." Although much has been learned, both technically to guide important policy decisions. Low frequency noise and socially, the process of identifying, quantifying, and alle- with its related vibration, meteorological, and topological viating noise effects of aviation remains an art. We now know data continue to drive modeling improvements, and correct that because aviation noise does not approximate those of some limited under-predictions of sideline-noise levels. occupational health criteria, hearing loss is unlikely; aviation Home property values may have limited relationship to noise noise effects do not influence newborn birth weight, and levels, and future research linked with powerful geographic annoyance may be largely influenced by non-acoustic factors. information system tools may provide new insights. Al- Sleep interference, with great variability between laboratory though long-term averages are typically used in conjunction and in-home studies, occurs much less than previously with land use planning and residential property location, new thought. We have also learned that cross-sectional studies are research indicates that the use of Leq (equivalent sound level) notoriously difficult to interpret, often report conflicting may display a greater accuracy in identifying areas most af- results, and do not result in dose-response relationships. fected by aviation noise. Investigations that report a distinct percentage of the pop- In conclusion, despite decades of research and new, well- ulation who are "highly annoyed" at any given day-night documented information, aviation noise effects continue to average noise level may be incorrectly interpreted as having be an enigma waiting to be solved.