ASA S12 9 PART 7-2016 American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound Part 7 Measurement of Low-frequency Noise and Infr.pdf

1、 ANSI/ASA S12.9-2016/Part 7 AMERICAN NATIONAL STANDARD Quantities and Procedures for Description and Measurement of Environmental Sound, Part 7: Measurement of Low-frequency Noise and Infrasound Outdoors and in the Presence of Wind and Indoors in Occupied Spaces Accredited Standards Committee S12, N

2、oise Standards Secretariat Acoustical Society of America 1305 Walt Whitman Road, Suite 300 Melville, NY 11747 ANSI/ASAS12.9-2016/Part7The American National Standards Institute, Inc. (ANSI) is the national coordinator of voluntary standards development and the clearinghouse in the U.S.A. for informat

3、ion on national and international standards. The Acoustical Society of America (ASA) is an organization of scientists and engineers formed in 1929 to increase and diffuse the knowledge of acoustics and to promote its practical applications. ANSI/ASA S12.9-2016/Part 7 AMERICAN NATIONAL STANDARD Quant

4、ities and Procedures for Description and Measurement of Environmental Sound, Part 7: Measurement of Low-frequency Noise and Infrasound Outdoors in the Presence of Wind and Indoors in Occupied Spaces Secretariat: Acoustical Society of America Approved on April 25, 2016, by: American National Standard

5、s Institute, Inc. Abstract Part 7 of the ANSI/ASA S12.9 series describes cautions and unique techniques for measuring low-frequency noise (LFN) outdoors in the presence of wind. It is necessary to measure in wind for wind turbine projects and for countless other industrial power and facilities where

6、 environmental wind speed cannot be controlled or levels are specified under downwind conditions. The standard also describes a uniform and repeatable methodology for documenting LFN levels and spectra indoors in occupied spaces where modal considerations are important. The principal concern outdoor

7、s is wind-induced noise (WIN) created by wind sources alone. The best estimates for WIN versus wind speed are presented herein based on the literature and special testing conducted by the working group for this standard. The standard is intended to define methods for routinely observed or monitored

8、measurements of infrasound and LFN (ILFN) with standard off-the-shelf instrumentation, commercially available or special windscreens, and microphones appropriate to the task at hand. Following the standard methods should promote uniform, repeatable, and comparable data from site to site. AMERICAN NA

9、TIONAL STANDARDS ON ACOUSTICS The Acoustical Society of America (ASA) provides the Secretariat for Accredited Standards Committees S1 on Acoustics, S2 on Mechanical Vibration and Shock, S3 on Bioacoustics, S3/SC 1 on Animal Bioacoustics, and S12 on Noise. These committees have wide representation fr

10、om the technical community (manufacturers, consumers, trade associations, organizations with a general interest, and government representatives). The standards are published by the Acoustical Society of America as American National Standards after approval by their respective Standards Committees an

11、d the American National Standards Institute (ANSI). These standards are developed and published as a public service to provide standards useful to the public, industry, and consumers, and to Federal, State, and local governments. Each of the Accredited Standards Committees (operating in accordance w

12、ith procedures approved by ANSI) is responsible for developing, voting upon, and maintaining or revising its own Standards. The ASA Standards Secretariat administers Committee organization and activity and provides liaison between the Accredited Standards Committees and ANSI. After the Standards hav

13、e been produced and adopted by the Accredited Standards Committees, and approved as American National Standards by ANSI, the ASA Standards Secretariat arranges for their publication and distribution. An American National Standard implies a consensus of those substantially concerned with its scope an

14、d provisions. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires th

15、at all views and objections be considered and that a concerted effort be made towards their resolution. The use of an American National Standard is completely voluntary. Their existence does not in any respect preclude anyone, whether he or she has approved the Standards or not, from manufacturing,

16、marketing, purchasing, or using products, processes, or procedures not conforming to the Standards. NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revi

17、se, or withdraw this Standard. Acoustical Society of America ASA Secretariat 1305 Walt Whitman Road, Suite 300 Melville, New York 11747 Telephone: 1 (631) 390-0215 Fax: 1 (631) 923-2875 E-mail: asastdsacousticalsociety.org 2016 by Acoustical Society of America. This standard may not be reproduced in

18、 whole or in part in any form for sale, promotion, or any commercial purpose, or any purpose not falling within the provisions of the U.S. Copyright Act of 1976, without prior written permission of the publisher. For permission, address a request to the Standards Secretariat of the Acoustical Societ

19、y of America. 2016 Acoustical Society of America All rights reserved iContents 1 Scope . 1 2 Normative references . 1 3 Terms and definitions . 2 4 Instrumentation 3 4.1 Instrumentation sets and measurement grades . 3 4.2 Survey-grade LFN 3 4.3 Survey-grade ILFN . 3 4.4 Precision-grade LFN . 3 4.5 P

20、recision-grade ILFN 4 5 Measurement metric 4 5.1 Basic metric 4 5.2 Supplemental metric . 4 6 Outdoor measurements . 4 6.1 Measurement types 4 6.2 Windscreen selection . 5 6.3 Estimation of lowest measurable frequency band 8 6.4 Reporting 9 7 Indoor measurements 10 7.1 General . 10 7.2 Winds 10 7.3

21、Measurement locations and descriptions . 10 7.4 Windscreen selection . 11 7.5 Analysis results . 11 7.6 Reporting 12 8 Signal processing techniques 13 Annex A (informative) Examples of outdoor/indoor measurement testing unsteady source . 14 A.1 Introduction . 14 A.2 Possible deviations . 14 A.3 Test

22、 results . 16 Annex B (informative) Development of wind-induced noise (WIN) estimates 19 Annex C (informative) Estimation of sound level spectra at normal above-grade microphone height from ground-plane results . 23 Annex D (informative) Advanced signal processing techniques . 25 D.1 Introduction .

23、25 D.2 Low-frequency wind turbine noise 25 D.3 Signal acquisition and analysis options 28 2016 Acoustical Society of America All rights reserved iiFigures Figure 1 Wind-induced noise (WIN) measurement setup; in the Mojave Desert (upper image) in California and western Oregon (lower image) . 5 Figure

24、 2a Measured A- and C- weighted wind-induced noise levels for a 175 mm 20 ppi windscreen . 6 Figure 2b Measured G-weighted wind-induced noise levels for a 175 mm 20 ppi windscreen . 6 Figure 3 Measured C- and G-weighted levels in the 6-7 m/s wind speed bin for the seven microphone setups in the Moha

25、ve Desert (see Annex B) . 7 Figure 4 Example of measured wind turbine generator (WTG) spectra for low and high wind conditions compared to wind-induced noise (WIN) . 9 Figure 5 Indoor test setup 11 Figure A.1 Depiction of measurement locations from inside interior space . 14 Figure A.2 Depiction of

26、measurement locations on exterior of interior space . 15 Figure A.3 Raw measurement data normalized to free field 15 Figure A.4 Noise reduction (NRe) for each of two trials . 16 Figure A.5 5-min duration Leq for outdoor and indoor measurement locations 17 Figure A.6 5-min duration Leq summary 18 Fig

27、ure C.1 Theoretical and measured corrections to convert from a ground-plane measurement to one at 1.5 m above grade to include ground-reflected wave 24 Tables Table B.1 Measured spectral wind-induced noise (WIN) at site W (Mojave Desert) for seven windscreen designs (continued on next page) 20 Table

28、 B.1 - Measured spectral wind-induced noise (WIN) at site W (Mojave Desert) for seven windscreen designs (page 2) . 21 Table B.2 Windscreen insertion loss 22 2016 Acoustical Society of America All rights reserved iiiForeword This Foreword is for information only, and is not a part of the American Na

29、tional Standard ANSI/ASA S12.9-2016/Part 7 American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound, Part 7: Measurement of Low-frequency Noise and Infrasound Outdoors in the Presence of Wind and Indoors in Occupied Spaces. As such, this Foreword ma

30、y contain material that has not been subjected to public review or a consensus process. In addition, it does not contain requirements necessary for conformance to the standard. This standard comprises a part of a group of definitions, standards, and specifications for use in noise. It was developed

31、and approved by Accredited Standards Committee S12 Noise, under its approved operating procedures. Those procedures have been accredited by the American National Standards Institute (ANSI). The Scope of Accredited Standards Committee S12 is as follows: Standards, specifications, and terminology in t

32、he field of acoustical noise pertaining to methods of measurement, evaluation, and control, including biological safety, tolerance, and comfort, and physical acoustics as related to environmental and occupational noise. This standard is a new part of the ANSI/ASA S12.9 series American National Stand

33、ard Quantities and Procedures for Description and Measurement of Environmental Sound. This standard is not comparable to any existing ISO Standard. At the time this Standard was submitted to Accredited Standards Committee S12 - Noise for approval, the membership was as follows: S.J. Lind, Chair D.F.

34、 Winker, Vice-Chair S.B. Blaeser, Secretary 3M Occupational Health FAX: 631-923-2875; E-mail: asastdsacousticalsociety.org. 2016 Acoustical Society of America All rights reserved vi Introduction Measuring outdoor sound pressure levels and spectra can be difficult in the presence of wind, even at ver

35、y low wind speeds often defined as “acceptable” in many measurement standards. Wind-induced noise (WIN) is the principal problem and can produce a false indicator of sound pressure at low frequencies mistaken for actual low-frequency noise when in fact no such low-frequency noise is present. WIN is

36、the sound that can be measured in remote quiet environments essentially free of all anthropogenic and natural sources of sound, except for wind-generated noise such as leaf noise and pseudo microphone noise. Experience shows that accurate outdoor measurements down to conventional frequency range lim

37、its (i.e., the 16 Hz or 31.5 Hz octave band) can only be made under nearly ideal “calm and still” conditions when using standard relatively small windscreens. Conditions are calm and still when there is no measurable wind speed at microphone height and no observable grass or tree leaf movement or au

38、dible sound. Note that this experience and statement applies to precision type 1 instrumentation while using the windscreen (60 to 90 mm diameter) furnished by the instrument supplier. Measuring the overall A-weighted outdoor level is much less of a problem due to the severe weighting of the A scale

39、 filter, but measuring the C- or G-weighted levels usually requires calm and still conditions or improved wind protection. The A-weighting filter may not be appropriate for evaluating low-frequency noise (LFN) or infrasonic-plus-low-frequency noise (ILFN). The procedures contained herein allow WIN t

40、o be estimated yielding the lowest levels for valid measurements in each frequency band in the presence of low to high wind speeds. WIN for seven improved windscreen designs have been measured and are tabulated herein. Using these data, one can separate true acoustic ILFN from wind-induced noise. Th

41、is information is also informative to instrumentation suppliers in the development of commercial products. Measurement of indoor sound at low frequencies is addressed, and a standard test measurement methodology is developed that should yield repeatable data from site to site and from one investigat

42、or to another. Acknowledgement The working group of volunteers for this standard has expended much time and effort in designing, fabricating, and testing improved windscreen devices to lower the valid frequency for which sound can be measured in the presence of wind. The results are contained in the

43、 standard and annexes. The chair would like to especially acknowledge the contribution of Dr. Bruce Walker of Channel Islands Acoustics for an extraordinary effort that far surpassed the considerable efforts of other members. AMERICAN NATIONAL STANDARD ANSI/ASA S12.9-2016/Part 7 2016 Acoustical Soci

44、ety of America All rights reserved 1American National Standard Quantities and Procedures for Description and Measurement of Environmental Sound, Part 7: Measurement of Low-frequency Noise and Infrasound Outdoors In the Presence of Wind and Indoors in Occupied Spaces 1 Scope This standard provides re

45、quirements and methods for measuring low-frequency sound and noise levels outdoors in the presence of wind and indoors in occupied spaces. The most common application anticipated is the measurement of outdoor immission levels either near or far from sound emission sources or emission levels near a s

46、ource. A repeatable method for measuring low-frequency levels and spectra indoors is given so that results can be compared from site to site or for repeated measurements at the same site under differing operating scenarios or time periods. The value of this method to indoor measurements is that wind

47、 effects on the microphone are eliminated. However, two new variables are introduced: wind impinging on a structure creates significant low-frequency noise that is difficult to quantify, and measuring indoors with room sizes comparable to or smaller than low-frequency wavelengths requires an account

48、ing of room resonance modes. Nevertheless, following the prescribed measurement technique in low-wind conditions should give a uniform repeatable method of measurement that accounts for differing room modes from space to space. The standard does not address all factors to be considered when measurin

49、g the emissions of sources or background sound levels in the environment that are covered in other standards. Such factors may be measurement metrics, duration of measurements, background corrections, time of day, and countless others. Usually, wind speeds in these specific standards are limited to low values (about 2 m/s or 5 mph) to minimize wind-induced noise effects. Measured data in the annexes show clearly that wind, even at these low wind speeds, significantly affects the measurements at very low frequencies. This standard is limite