Appendix E
Modern Instrumentation for Environmental Noise Measurement

The science of environmental noise measurement has progressed rapidly in the past decade as computer technology has come online to provide rapid data acquisition and analysis in small portable packages. The end result has been a revolution in the type and complexity of measurements and calculations that can be made in analyzing environmental noise. The bulk of this discussion will be focused on the capabilities of modern measurement systems. Both sound-level meters and monitoring systems will be discussed in some detail. Finally, a summary of the findings from this analysis will be presented as to the capabilities and limitations of current measurements. Whether there are restrictions on the types of metrics that could be utilized in defining and limiting environmental noise will also be discussed.

The equations used to calculate the various metrics are not discussed here. The American National Standards Institute has a series of standards, the S12.9 series, listed as references in this appendix. Part 4 is particularly relevant to the mathematical definition of metrics for community noise. These standards are developed by ANSI Committee S12—Noise and are available through the Acoustical Society of America (ASA, 2010).

Sound-level meters and related filter characteristics have been standardized by the American National Standards Institute and are also available through the Acoustical Society of America (http://asastore.aip.org/shop.do?cID=7). International standards on the same subjects are developed by the International Electrotechnical Commission Technical Committee 29—Electroacoustics (IEC, 2010).

SOUND-LEVEL METERS

The Brüel & Kjær Type 2270 sound-level meter is a modern instrument and will be used as the typical example for this discussion. Other manufacturers make instruments with similar capabilities. This is an integrating sound-level meter with the ability to compute sound energy summations. This is the standard sort of capability found in high-end sound-level meters. There is a large amount of computing power using microprocessors built into the unit. This allows for sophisticated analysis, data communication, and programming. Figures E-1 and E-2 show examples of the screen display and use of this meter.

The types or measurements possible with this meter are listed below:

  • for display and storage: Ldn, Lden, Lday, Levening, and Lnight

  • selectable day, evening and night periods and penalties

FIGURE E-1 Screen display of discrete frequency analysis for Type 2270 monitor. Copyright © Brüel & Kjær.

FIGURE E-1 Screen display of discrete frequency analysis for Type 2270 monitor. Copyright © Brüel & Kjær.



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Appendix E Modern Instrumentation for Environmental Noise Measurement The science of environmental noise measurement has meters. There is a large amount of computing power using progressed rapidly in the past decade as computer technol- microprocessors built into the unit. This allows for sophis- ogy has come online to provide rapid data acquisition and ticated analysis, data communication, and programming. analysis in small portable packages. The end result has been Figures E-1 and E-2 show examples of the screen display a revolution in the type and complexity of measurements and and use of this meter. calculations that can be made in analyzing environmental The types or measurements possible with this meter are noise. The bulk of this discussion will be focused on the ca- listed below: pabilities of modern measurement systems. Both sound-level meters and monitoring systems will be discussed in some • for display and storage: Ldn, Lden, Lday, Levening, and detail. Finally, a summary of the findings from this analysis Lnight will be presented as to the capabilities and limitations of • selectable day, evening and night periods and penal- current measurements. Whether there are restrictions on the ties types of metrics that could be utilized in defining and limiting environmental noise will also be discussed. The equations used to calculate the various metrics are not discussed here. The American National Standards Institute has a series of standards, the S12.9 series, listed as references in this appendix. Part 4 is particularly relevant to the math- ematical definition of metrics for community noise. These standards are developed by ANSI Committee S12—Noise and are available through the Acoustical Society of America (ASA, 2010). Sound-level meters and related filter characteristics have been standardized by the American National Standards Institute and are also available through the Acoustical So- ciety of America (http://asastore.aip.org/shop.do?cID=7). International standards on the same subjects are developed by the International Electrotechnical Commission Technical Committee 29—Electroacoustics (IEC, 2010). SOuND-LEVEL METERS The Brüel & Kjær Type 2270 sound-level meter is a modern instrument and will be used as the typical example for this discussion. Other manufacturers make instruments with similar capabilities. This is an integrating sound-level meter with the ability to compute sound energy summations. This is FIGURE E-1 Screen display of discrete frequency analysis for the standard sort of capability found in high-end sound-level Type 2270 monitor. Copyright © Brüel & Kjær. Figure_E-1.eps bitmap 7

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8 TECHNOLOGY FOR A QUIETER AMERICA FIGURE E-2 Type 2270 meter in use. Copyright © Brüel & Kjær. Figure_E-2.eps bitmap • report period: from 1 minute to 24 hours with 1-minute resolution • all broadband data and statistics stored at each report- ing interval FIGURE E-3 Typey3639 monitoring station. Copyright © Brüel Figure E-3 T pe 3639 monitoring station. • all spectrum data stored at each reporting interval • spectral statistics stored at each reporting interval & Kjær. • logging time: from 1 second to 31 days with 1 second resolution or continuous • data are saved in separate projects for every 24 hours of logging • postprocessing that can create periodic statistical re- ports down to 1 minute, including LN data NOISE MONITORINg SySTEMS • GPS support • sound recording The sound-level meter market can be divided into three • weather data monitoring levels. The high end is the integrating analyzer with a tre- • camera support mendous amount of computing power. Some manufacturers • remote operation via LAN, public telephone lines, mo- use a laptop computer attached to the instrument for this bile phone, or General Packet Radio Service (GPRS) category. At the lowest level, these instruments are meters that can merely report a sound level. The definition of the measurements that can be done with The Brüel & Kjær Type 3639 Noise Monitoring Terminal these types of monitoring stations is quite lengthy. A short will be used as the example for this discussion. There are summary is presented here of typical calculations. several competing products by other manufacturers with very similar capabilities. The Type 3639 is designed for use Broadband values: in all climate environments, as well as industrial, urban, • X = frequency weightings A and C, or A and Linear, and rural conditions. It can be left unattended as part of or C and Linear (two weightings simultaneously) an environmental noise monitoring system for permanent, • Y = time weightings Fast, Slow and Impulse (all mobile, or semipermanent monitoring. The Noise Monitor- simultaneously) ing Terminal can be controlled by a remote PC. This unit is • LXeq, LXpeak, LXim, LXYinst, LXYmax/SPL, LXYmin shown in Figure E-3. Typical capabilities for these types of monitoring systems Spectrum values: are summarized here: • equivalent continuous level (Leq) and I-weighted value also selectable (LAIeq) • logging of broadband and 1/3-octave parameters every • 1/3-octave frequency range: 12.5 to 20 kHz second or half-second

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 APPENDIX E Events: 2002/49/EC and similar statutes in other parts of the world • settings: hourly, user-defined on the following has also been a major driver for the acquisition and use of parameters: monitoring systems. Cities, counties, countries, and indus- • detection: separate event start/stop triggers tries are obliged to follow the national and local legislation • event start trigger: Leq or SPL with minimum thresh- and the standard that defines measurement and estimation old exceedence duration of noise in the environment. In many instances the demand • event stop trigger: Leq or SPL with minimum thresh- is driven by a desire to have a positive relationship with the old exceedence duration public. There is also increased attention to quality of life. Public pressure on noisy transportation systems (roads and Table E-1 is a summary of the hardware options offered by rail), industries (metal, chemical, mining, and construction), the Brüel & Kjær system to illustrate the variety available. In and communities to manage and inform on environmental addition, there is a wide array of software options as shown issues has been a driver for the use of monitoring systems in in Table E-2. One will note that all the energy summation the urban environment. options and most of the other metrics noted previously are included in the available software. MONITORINg DEMAND DRIVERS—AIRPORT NOISE For airports, the major driver in the use of monitoring MONITORINg DEMAND DRIVERS—uRBAN NOISE systems is to optimize profit or capacity. By carefully moni - The drivers of the demand for monitoring systems have toring noise, airports can increase movements and hence been studied extensively by manufacturers, including Brüel profits by increasing the environmental capacity. It allows & Kjær (Denmark), Lochard (Australia, mostly focused on them to optimize the capacity utilization. An airport can also monitoring airport noise), 01dB-Metravib (France, mostly postpone or even avoid the need for new infrastructure such focused on monitoring urban noise), and Norsonic/Topsonic as runways, taxiways, or terminals by maximizing use of the (Germany and Norway, a software partner of Norsonic on available land and runways. large systems). It is also necessary to manage relationships with regula- A primary influence is the need to meet the monitoring tory bodies. This includes the use of monitoring equipment requirement dictated by legislation and standards. Imple- with regard to legislation, standards such as ISO 1996 Envi- mentation of European Union environmental noise directive ronmental Noise Assessment, Part 1 (definitions) published TABLE E-1 Hardware Options for Brüel & Kjær Monitoring Systems Application Key Features Products and Their Key Features #) 4198 Outdoor Microphone Unit 6) Airport Noise Monitoring 1) LAeq Lmax 4184 Weatherproof Microphone Unit 6) Urban Noise Monitoring 2) Statistics LN 3631 Portable Noise Monitoring Terminal 1) 2) 16) 17) Plant Noise Monitoring 3) 1/3 Octave spectra 3637 Portable Noise Monitoring Terminal 1) 2) 3) 4) 5) 6) 7) 9) 16) 17) 4) Event trigger 3597 Permanent Noise Monitoring Terminal 1) 2) 3) 4) 5) 6) 7) 9) 16) 5) Sound/Video recording 7802 Noise Monitoring Software 4) 8) 10) 14) 15) 16) 6) Automatic Calibration (CIC) 7840 Noise Monitoring Software 8) 10) 14) 15) 16) 7) Automatic location (GPS) 7832 Reporting Module 11) 8) Communication with NMT 7833 Complaints Module 12) 9) EPNL 7804 Flight Tracking Option 13) 14) 10) Database management 7834 INM Link 15) 11) Reporting 12) Complaints handling 13) Correlation with flights 14) GIS Interface 15) Prediction 16) Weather information

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60 TECHNOLOGY FOR A QUIETER AMERICA TABLE E-2 Software Options for Brüel & Kjær Monitoring Systems Application Key Features Products and Their Key Features #) Modelling outdoor noise Noise level mapping 7810 Predictor Environmental impact assessments 7812 Lima Scenario comparison Fulfil EU IPPC 1996/61/EEC Large-scale noise mapping Fulfil EU END 2002/49/EC (for example, interim methods) 7812 Lima Large-scale data handling Interface with external databases and software 2260 Investigator 1) 2) 3) 5) Measuring sound powers of noise sources 1) Sound intensity method 2260 Observer 2) 3) 5) 2) Sound pressure method 2250 Hand-held Analyzer 2) 3) Validating calculations 3) LAeq 7816 Acoustic Determinator 2) 3) 4) LDEN 3637 Noise Monitoring Terminal 3) 5) 5) GPS position 3631 Noise Monitoring Terminal 3) 3597 Noise Monitoring Terminal 3) 5) 7802/40 Noise Monitoring Software 3) 4) 5) Airport noise maps Noise level mapping 7834 INM Link Import of actual flight information Modelling aircraft noise Noise level mapping 7812 Lima Footprints and time histories 2003, Part 2 (assessment techniques) DIS 2005, and ISO Each segment represents a need for different types of 20906 Aircraft Noise Monitoring (major revision of ISO software and hardware. In the case of short-term monitor- 3891-1978). Finally, there is the need to manage relation- ing, a sound-level meter may be sufficient. For permanent ships with adjacent communities. One way to accomplish monitoring a self-contained monitoring unit is required, and this is to monitor and be able to provide noise levels to refute on-board analysis capabilities are probably desirable. complaints and to demonstrate action to monitor and control noise levels. SuMMARy A large number of metrics are currently being used, MONITORINg MARKET SEgMENTATION ranging from A-weighted sound levels to day-evening-night One way to understand how this market is segmented is average sound pressure levels with various corrections. There to look at the interests of customers: are still some issues when it comes to low-frequency noise, impulsive sounds, and certain sources—special cases may 1. Airport noise require unique metrics. Undoubtedly, new and more complex 2. Urban noise metrics will be developed. 3. City noise Sophisticated modern sound-level meters and monitor- 4. Road noise ing devices have the capability to record and report any 5. Railway noise metric that can be programmed. The level of sophistication 6. Industry—internal (facilities) and external (products) currently available is sufficient to perform measurements 7. Construction sites and calculations required by all current metrics and some 8. Recreational areas of the metrics used in product sound quality evaluation. These sound quality metrics may become more widespread In each customer segment the buyer can be either the in the future for the evaluation of community noise. The use final customer, a consultant, or a system integrator. Another of modern computer technology has effectively eliminated way to break down the marketplace is to look at solution any limitations on measurement equipment in terms of the segments: metrics that can be used. Data management is now much easier. Embedding 1. short-term monitoring large amounts of memory in instrumentation is relatively 2. long-term monitoring inexpensive and wireless connection capability also means 3. permanent monitoring that a large amount of data can now be collected and stored automatically for future processing, which greatly facilitates

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6 APPENDIX E testing of proposed new metrics. It also means that the noise vironmental Sound, Part 2: Measurement of Long-Term, Wide Area Sound measurement component of large community surveys can • ANSI/ASA S12.9-1993/Part 3 (R2008)—American National Stan- be approached in a very different way from the way it was dard Quantities and Procedures for Description and Measurement done in the past when data collection, memory, and storage of Environmental Sound, Part 3: Short-Term Measurements with an capabilities were very limited. Observer In the competitive marketplace for sound-level meters and • ANSI S12.9-2005/Part 4 American National Standard Quantities and Procedures for Description and Measurement of Environmental monitoring systems, the same sort of capability is available Sound—Part 4: Noise Assessment and Prediction of Long-Term from several vendors. Prices and performance will continue Community Response. to improve. • ANSI/ASA S12.9-2007/Part 5 American National Standard Quanti- ties and Procedures for Description and Measurement of Environ - mental Sound—Part 5: Sound-Level Descriptors for Determination REFERENCES of Compatible Land Use • ANSI/ASA S12.9-2008/Part 6 American National Standard Quan- ASA. 2010. American National Standards Institute, ASC S1—Physical tities and Procedures for Description and Measurement of Envi- Acoustics. ASC S1 standards are available online from the Acoustical ronmental Sound—Part 6: Methods for Estimation of Awakenings Society of America at http://asastore.aip.org/shop.do?cID=7. The fol- Associated with Outdoor Noise Events Heard in Homes lowing is a list of the standards available in the S12.9 series: IEC. 2010. Technical Committee 29—Electroacoustics, International • ANSI S12.9-1988 (R 2003) American National Standard Quantities Electrotechnical Commission, Geneva, Switzerland. Available on- and Procedures for Description and Measurement of Environmental line at h ttp://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwla Sound, Part 1 ng=e&wwwprog=TCpubs.p&progdb=db&committee=TC&css_ • ANSI/ASA S12.9-1992/Part 2 (R2008) American National Standard color=purple&number=. Quantities and Procedures for Description and Measurement of En-

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