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Technology for a Quieter America (2010)

Chapter: Appendix E: Modern Instrumentation for Environmental Noise Measurement

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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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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.

Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×
FIGURE E-2 Type 2270 meter in use. Copyright © Brüel & Kjær.

FIGURE E-2 Type 2270 meter in use. Copyright © Brüel & Kjær.

  • report period: from 1 minute to 24 hours with 1-minute resolution

  • all broadband data and statistics stored at each reporting interval

  • all spectrum data stored at each reporting interval

  • spectral statistics stored at each reporting interval

  • 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

NOISE MONITORING SYSTEMS

The sound-level meter market can be divided into three levels. The high end is the integrating analyzer with a tremendous amount of computing power. Some manufacturers use a laptop computer attached to the instrument for this category. At the lowest level, these instruments are meters that can merely report a sound level.

The Brüel & Kjær Type 3639 Noise Monitoring Terminal will be used as the example for this discussion. There are several competing products by other manufacturers with very similar capabilities. The Type 3639 is designed for use in all climate environments, as well as industrial, urban, and rural conditions. It can be left unattended as part of an environmental noise monitoring system for permanent, mobile, or semipermanent monitoring. The Noise Monitoring Terminal can be controlled by a remote PC. This unit is shown in Figure E-3.

Typical capabilities for these types of monitoring systems are summarized here:

  • logging of broadband and 1/3-octave parameters every second or half-second

FIGURE E-3 Type 3639 monitoring station. Copyright © Brüel & Kjær.

FIGURE E-3 Type 3639 monitoring station. Copyright © Brüel & Kjær.

  • postprocessing that can create periodic statistical reports down to 1 minute, including LN data

  • GPS support

  • sound recording

  • weather data monitoring

  • camera support

  • remote operation via LAN, public telephone lines, mobile phone, or General Packet Radio Service (GPRS)

The definition of the measurements that can be done with these types of monitoring stations is quite lengthy. A short summary is presented here of typical calculations.


Broadband values:

  • X = frequency weightings A and C, or A and Linear, or C and Linear (two weightings simultaneously)

  • Y = time weightings Fast, Slow and Impulse (all simultaneously)

  • LXeq, LXpeak, LXim, LXYinst, LXYmax/SPL, LXYmin

Spectrum values:

  • equivalent continuous level (Leq) and I-weighted value also selectable (LAIeq)

  • 1/3-octave frequency range: 12.5 to 20 kHz

Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

Events:

  • settings: hourly, user-defined on the following parameters:

  • detection: separate event start/stop triggers

  • event start trigger: Leq or SPL with minimum threshold exceedence duration

  • event stop trigger: Leq or SPL with minimum threshold exceedence duration

Table E-1 is a summary of the hardware options offered by the Brüel & Kjær system to illustrate the variety available. In addition, there is a wide array of software options as shown in Table E-2. One will note that all the energy summation options and most of the other metrics noted previously are included in the available software.

MONITORING DEMAND DRIVERS—URBAN NOISE

The drivers of the demand for monitoring systems have been studied extensively by manufacturers, including Brüel & Kjær (Denmark), Lochard (Australia, mostly focused on monitoring airport noise), 01dB-Metravib (France, mostly focused on monitoring urban noise), and Norsonic/Topsonic (Germany and Norway, a software partner of Norsonic on large systems).

A primary influence is the need to meet the monitoring requirement dictated by legislation and standards. Implementation of European Union environmental noise directive 2002/49/EC and similar statutes in other parts of the world has also been a major driver for the acquisition and use of monitoring systems. Cities, counties, countries, and industries are obliged to follow the national and local legislation and the standard that defines measurement and estimation of noise in the environment. In many instances the demand is driven by a desire to have a positive relationship with the public. There is also increased attention to quality of life. Public pressure on noisy transportation systems (roads and rail), industries (metal, chemical, mining, and construction), and communities to manage and inform on environmental issues has been a driver for the use of monitoring systems in the urban environment.

MONITORING DEMAND DRIVERS—AIRPORT NOISE

For airports, the major driver in the use of monitoring systems is to optimize profit or capacity. By carefully monitoring noise, airports can increase movements and hence profits by increasing the environmental capacity. It allows them to optimize the capacity utilization. An airport can also postpone or even avoid the need for new infrastructure such as runways, taxiways, or terminals by maximizing use of the available land and runways.

It is also necessary to manage relationships with regulatory bodies. This includes the use of monitoring equipment with regard to legislation, standards such as ISO 1996 Environmental Noise Assessment, Part 1 (definitions) published

TABLE E-1 Hardware Options for Brüel & Kjær Monitoring Systems

Application

Key Features

Products and Their Key Features #)

Airport Noise Monitoring

1) LAeq Lmax

4198 Outdoor Microphone Unit 6)

Urban Noise Monitoring

2) Statistics LN

4184 Weatherproof Microphone Unit 6)

Plant Noise Monitoring

3) 1/3 Octave spectra

3631 Portable Noise Monitoring Terminal 1) 2) 16) 17)

 

4) Event trigger

3637 Portable Noise Monitoring Terminal 1) 2) 3) 4) 5) 6) 7) 9) 16) 17)

 

5) Sound/Video recording

3597 Permanent Noise Monitoring Terminal 1) 2) 3) 4) 5) 6) 7) 9) 16)

 

6) Automatic Calibration (CIC)

7802 Noise Monitoring Software 4) 8) 10) 14) 15) 16)

 

7) Automatic location (GPS)

7840 Noise Monitoring Software 8) 10) 14) 15) 16)

 

8) Communication with NMT

7832 Reporting Module 11)

 

9) EPNL

7833 Complaints Module 12)

 

10) Database management

7804 Flight Tracking Option 13) 14)

 

11) Reporting

7834 INM Link 15)

 

12) Complaints handling

 

 

13) Correlation with flights

 

 

14) GIS Interface

 

 

15) Prediction

 

 

16) Weather information

 

Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

TABLE E-2 Software Options for Brüel & Kjær Monitoring Systems

Application

Key Features

Products and Their Key Features #)

Modelling outdoor noise

Noise level mapping

Environmental impact assessments

Scenario comparison

Fulfil EU IPPC 1996/61/EEC

7810 Predictor

7812 Lima

Large-scale noise mapping

Fulfil EU END 2002/49/EC (for example, interim methods)

Large-scale data handling

Interface with external databases and software

7812 Lima

Measuring sound powers of noise sources

1) Sound intensity method

2) Sound pressure method

3) LAeq

4) LDEN

5) GPS position

2260 Investigator 1) 2) 3) 5)

2260 Observer 2) 3) 5)

2250 Hand-held Analyzer 2) 3)

7816 Acoustic Determinator 2) 3)

3637 Noise Monitoring Terminal 3) 5)

3631 Noise Monitoring Terminal 3)

3597 Noise Monitoring Terminal 3) 5)

7802/40 Noise Monitoring Software 3) 4) 5)

Validating calculations

Airport noise maps

Noise level mapping

Import of actual flight information

7834 INM Link

Modelling aircraft noise

Noise level mapping

Footprints and time histories

7812 Lima

2003, Part 2 (assessment techniques) DIS 2005, and ISO 20906 Aircraft Noise Monitoring (major revision of ISO 3891-1978). Finally, there is the need to manage relationships with adjacent communities. One way to accomplish this is to monitor and be able to provide noise levels to refute complaints and to demonstrate action to monitor and control noise levels.

MONITORING MARKET SEGMENTATION

One way to understand how this market is segmented is to look at the interests of customers:

  1. Airport noise

  2. Urban noise

  3. City noise

  4. Road noise

  5. Railway noise

  6. Industry—internal (facilities) and external(products)

  7. Construction sites

  8. Recreational areas

In each customer segment the buyer can be either the final customer, a consultant, or a system integrator. Another way to break down the marketplace is to look at solution segments:

  1. short-term monitoring

  2. long-term monitoring

  3. permanent monitoring

Each segment represents a need for different types of software and hardware. In the case of short-term monitoring, a sound-level meter may be sufficient. For permanent monitoring a self-contained monitoring unit is required, and on-board analysis capabilities are probably desirable.

SUMMARY

A large number of metrics are currently being used, ranging from A-weighted sound levels to day-evening-night average sound pressure levels with various corrections. There are still some issues when it comes to low-frequency noise, impulsive sounds, and certain sources—special cases may require unique metrics. Undoubtedly, new and more complex metrics will be developed.

Sophisticated modern sound-level meters and monitoring devices have the capability to record and report any metric that can be programmed. The level of sophistication currently available is sufficient to perform measurements and calculations required by all current metrics and some of the metrics used in product sound quality evaluation. These sound quality metrics may become more widespread in the future for the evaluation of community noise. The use of modern computer technology has effectively eliminated any limitations on measurement equipment in terms of the metrics that can be used.

Data management is now much easier. Embedding large amounts of memory in instrumentation is relatively inexpensive and wireless connection capability also means that a large amount of data can now be collected and stored automatically for future processing, which greatly facilitates

Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

testing of proposed new metrics. It also means that the noise measurement component of large community surveys can be approached in a very different way from the way it was done in the past when data collection, memory, and storage capabilities were very limited.

In the competitive marketplace for sound-level meters and monitoring systems, the same sort of capability is available from several vendors. Prices and performance will continue to improve.

REFERENCES

ASA. 2010. American National Standards Institute, ASC S1—Physical Acoustics. ASC S1 standards are available online from the Acoustical Society of America at http://asastore.aip.org/shop.do?cID=7. The following is a list of the standards available in the S12.9 series:

  • ANSI S12.9-1988 (R 2003) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound, Part 1

  • ANSI/ASA S12.9-1992/Part 2 (R2008) American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound, Part 2: Measurement of Long-Term, Wide Area Sound

  • ANSI/ASA S12.9-1993/Part 3 (R2008)—American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound, Part 3: Short-Term Measurements with an Observer

  • ANSI S12.9-2005/Part 4 American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound—Part 4: Noise Assessment and Prediction of Long-Term Community Response.

  • ANSI/ASA S12.9-2007/Part 5 American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound—Part 5: Sound-Level Descriptors for Determination of Compatible Land Use

  • ANSI/ASA S12.9-2008/Part 6 American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound—Part 6: Methods for Estimation of Awakenings Associated with Outdoor Noise Events Heard in Homes

IEC. 2010. Technical Committee 29—Electroacoustics, International Electrotechnical Commission, Geneva, Switzerland. Available online at http://www.iec.ch/cgi-bin/procgi.pl/www/iecwww.p?wwwlang=e&wwwprog=TCpubs.p&progdb=db1&committee=TC&css_color=purple&number=29.

Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×

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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×
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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×
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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×
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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×
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Suggested Citation:"Appendix E: Modern Instrumentation for Environmental Noise Measurement." National Academy of Engineering. 2010. Technology for a Quieter America. Washington, DC: The National Academies Press. doi: 10.17226/12928.
×
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Exposure to noise at home, at work, while traveling, and during leisure activities is a fact of life for all Americans. At times noise can be loud enough to damage hearing, and at lower levels it can disrupt normal living, affect sleep patterns, affect our ability to concentrate at work, interfere with outdoor recreational activities, and, in some cases, interfere with communications and even cause accidents. Clearly, exposure to excessive noise can affect our quality of life.

As the population of the United States and, indeed, the world increases and developing countries become more industrialized, problems of noise are likely to become more pervasive and lower the quality of life for everyone. Efforts to manage noise exposures, to design quieter buildings, products, equipment, and transportation vehicles, and to provide a regulatory environment that facilitates adequate, cost-effective, sustainable noise controls require our immediate attention.

Technology for a Quieter America looks at the most commonly identified sources of noise, how they are characterized, and efforts that have been made to reduce noise emissions and experiences. The book also reviews the standards and regulations that govern noise levels and the federal, state, and local agencies that regulate noise for the benefit, safety, and wellness of society at large. In addition, it presents the cost-benefit trade-offs between efforts to mitigate noise and the improvements they achieve, information sources available to the public on the dimensions of noise problems and their mitigation, and the need to educate professionals who can deal with these issues.

Noise emissions are an issue in industry, in communities, in buildings, and during leisure activities. As such, Technology for a Quieter America will appeal to a wide range of stakeholders: the engineering community; the public; government at the federal, state, and local levels; private industry; labor unions; and nonprofit organizations. Implementation of the recommendations in Technology for a Quieter America will result in reduction of the noise levels to which Americans are exposed and will improve the ability of American industry to compete in world markets paying increasing attention to the noise emissions of products.

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