Assessing Aircraft Noise Conditions Affecting Student Learning, Volume 1: Final Report (2014)

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CHAPTER 3. GAPS IN KNOWLEDGE AND FUTURE RESEARCH 3.1. Summary of Research Findings The previous section of this report provides a critical review and evaluation of research conducted on the effect of noise on children’s cognitive performance and learning, with emphasis on the effects of aircraft noise. From this review, it is now possible to identify the gaps in knowledge on solutions to the child learning problem that can form the basis of a research plan to meet the specific objectives of this project, namely: 1. Identify and evaluate conditions under which aircraft noise affects student learning. 2. Identify suitable noise metrics that best define those conditions. 3. Identify the most effective of the current criteria for school sound insulation projects. The gaps in knowledge to be identified will be those germane to these objectives and to the type of mitigation actions available to airport authorities. The most expedient way to identify gaps in knowledge is by setting forth a list of questions that need to be answered, and examining the scientific literature for answers to those questions. Potential gaps in knowledge will then be determined by the extent to which the literature cannot answer the questions. The questions that we will use in this evaluation are as follows: 1. To what extent is student learning affected by aircraft noise? 2. What is the most appropriate noise metric for describing aircraft noise as it affects learning? 3. What is the threshold above which the effect is observable? 4. Has sound insulation meeting existing classroom criteria improved student performance? 5. How does aircraft noise effect learning for students with different characteristics? The findings related to these questions that are offered by the scientific literature reviewed in Chapter 2 are presented in Table C.1 of Appendix C. The same scientific literature also recommends areas of further research, from which gaps in knowledge can be identified with respect to the above questions and the objectives of this project. These recommendations are listed in Table C.2 of Appendix C. 3.2. Summary of Gaps in Knowledge The summary of research findings and listing of the gaps in knowledge germane to the research objectives of this project can be summarized as follows: To what extent is student learning affected by aircraft noise? Developing further knowledge about exposure-effect relationships will inform decisions concerning the design of physical, educational, and psychological interventions for children exposed to high levels of noise. Such relationships can be assessed using either individually collected cognitive performance data or via school-level test data. 3-1

Whereas previous studies have demonstrated effects of chronic aircraft noise exposure on children’s reading comprehension and memory, it must be acknowledged that the majority of the evidence comes from cross-sectional studies. The development of cognitive abilities such as reading are important not only in terms of educational achievement but also for subsequent life chances and adult health (Kuh and Ben-Shlomo, 2004). To understand the causal pathways between noise exposure and cognition, and design preventive interventions there is a need to study these associations longitudinally. Few longitudinal studies have examined the effects of persistent exposure throughout the child’s education: studies of the long-term consequences of noise exposure during school for later cognitive development and educational outcomes have not yet been conducted and remain of prime policy importance. What is the most appropriate noise metric for describing aircraft noise as it affects learning? By far the majority of recent studies have relied on the established metric of average external noise exposure, LAeq, with the average taken over an 8-hour school day or over 16 daytime hours. While average exposure metrics demonstrate effects on children’s learning little is known about the effect of the number of noise events or the importance of peak sound events in noise effects on children’s learning. Two recent studies have suggested that peak sound events and the number of noise events could be important (Astolfi and Pellerey, 2008; Shield and Dockrell, 2008). Future studies should incorporate a range of additional noise metrics and examine their associations with children’s learning and cognitive performance to explore noise characterization in more detail. Such studies could also be informative for examining mechanisms for effects. What is the threshold above which the effect is observable? Recent evidence of exposure-effect relationships between aircraft noise exposure and children’s cognition has provided knowledge about thresholds for effects, further informing the design of interventions for children exposed to high levels of aircraft noise. Further examination of exposure-effect relationships in different contexts, for different samples and vulnerable groups, and for different noise metrics remains a research priority. Has insulation meeting existing classroom acoustic criteria improved student achievement? Given the evidence that aircraft noise is related to impairment of school performance, the question of what can be done to reduce noise induced learning impairments becomes salient. One possibility is reduction of external sound in the classroom through sound insulation. However, there has been little research testing whether sound insulation of classrooms might lessen the effects of aircraft noise on children’s learning (Bronzaft, 1981). While the recent FICAN study addressed this issue (Eagan, Anderson, Nicholas, et al, 2004), it was carried out on a small sample of schools which may not be representative. Future research needs to examine whether learning impairments related to aircraft noise can be reduced by sound insulation of the classroom in large-scale studies. Building on previous research, such studies could employ several types of methodology. Before-and-after studies of schools where insulation has been installed could be carried out at the school level, examining associations between external measures of aircraft noise exposure and standardized exam results for the school, taking school- level assessments of socioeconomic status into account. The FICAN pilot study is an example of this type of study (Eagan, Anderson, Nicholas, et al, 2004) but future studies would need to be 3-2

on a much larger scale. Opportunities to conduct naturally occurring before-and-after experiments, where schools are already being insulated should be taken advantage of. The literature suggests an increasingly important role of classroom acoustics on performance (Shield and Dockrell, 2008): however, it could be difficult to incorporate internal classroom acoustical factors into a study. In their study of noise exposure and national test scores for elementary school children, Shield and Dockrell (2008) successfully included internal acoustics in a sub-sample of 16 out of 142 schools: this illustrates the difficulties and potential lack of power of including classroom acoustics in such studies. How does aircraft noise affect learning for students with different characteristics? While the recent RANCH study has considerably advanced knowledge about exposure- effect relationships between noise and children’s cognition and health, further demonstration of exposure-effect relationships in different contexts and for different samples and vulnerable groups remains a research priority. 3-3