ANSI ASA S1.17 PART 1-2014 American National Standard Microphone Windscreens C Part 1 Test Procedures for Measurements of Insertion Loss in Still Air.pdf

1、 ANSI/ASA S1.17-2014/Part 1 (Revision of ANSI S1.17-2004/Part 1) AMERICAN NATIONAL STANDARD Microphone Windscreens Part 1: Test Procedures for Measurements of Insertion Loss in Still Air Accredited Standards Committee S1, Acoustics Standards Secretariat Acoustical Society of America 35 Pinelawn Road

2、, Suite 114 E Melville, NY 11747-3177ANSI/ASA S1.17-2014/Part 1 The American National Standards Institute, Inc. (ANSI) is the national coordinator of voluntary standards development and the clearinghouse in the U.S.A. for information on national and international standards. The Acoustical Society of

3、 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 S1.17-2014/Part 1 (Revision of ANSI S1.17-2004/Part 1) AMERICAN NATIONAL STANDARD Microphone Windscreens Part 1: Test Pr

4、ocedures for Measurements of Insertion Loss in Still Air Secretariat: Acoustical Society of America Approved on April 29, 2014, by: American National Standards Institute, Inc. Abstract This standard describes test procedures for determining the insertion loss of windscreens mounted on measurement mi

5、crophones. Insertion loss is determined over a specified frequency range and for still-air conditions in the test facility. AMERICAN NATIONAL STANDARDS ON ACOUSTICS The Acoustical Society of America (ASA) provides the Secretariat for Accredited Standards Committees S1 on Acoustics, S2 on Mechanical

6、Vibration and Shock, S3 on Bioacoustics, S3/SC 1 on Animal Bioacoustics, and S12 on Noise. These committees have wide representation from the technical community (manufacturers, consumers, trade associations, organizations with a general interest, and government representatives). The standards are p

7、ublished by the Acoustical Society of America as American National Standards after approval by their respective Standards Committees and the American National Standards Institute (ANSI). These standards are developed and published as a public service to provide standards useful to the public, indust

8、ry, and consumers, and to Federal, State, and local governments. Each of the Accredited Standards Committees (operating in accordance with procedures approved by ANSI) is responsible for developing, voting upon, and maintaining or revising its own standards. The ASA Standards Secretariat administers

9、 Committee organization and activity and provides liaison between the Accredited Standards Committees and ANSI. After the standards have been produced and adopted by the Accredited Standards Committees, and approved as American National Standards by ANSI, the ASA Standards Secretariat arranges for t

10、heir publication and distribution. An American National Standard implies a consensus of those substantially concerned with its scope and provisions. Consensus is established when, in the judgment of the ANSI Board of Standards Review, substantial agreement has been reached by directly and materially

11、 affected interests. Substantial agreement means much more than a simple majority, but not necessarily unanimity. Consensus requires that 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 volunt

12、ary. Their existence does not in any respect preclude anyone, whether he or she has approved the standards or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standards. NOTICE: This American National Standard may be revised or withdra

13、wn at any time. The procedures of the American National Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Acoustical Society of America ASA Secretariat 35 Pinelawn Road, Suite 114E Melville, New York 11747-3177 Telephone: +1 (631) 390-0215

14、Fax: +1 (631) 390-0217 E-mail: asastdsaip.org 2014 by Acoustical Society of America. This standard may not be reproduced in 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 w

15、ritten permission of the publisher. For permission, address a request to the Standards Secretariat of the Acoustical Society of America. 2014 Acoustical Society of America All rights reserved i Contents 1 Scope 1 2 Normative references .1 3 Terms and definitions .2 4 General requirements .4 5 Test e

16、nvironmental conditions 4 6 Test sound generating and measuring systems .4 7 Acoustical sensitivity of the sound-measurement system 5 8 Ambient sound pressure level 5 9 Measurement of windscreen insertion-loss in an anechoic or hemi-anechoic test space 6 9.1 Test space .6 9.2 Test signals 6 9.3 Soun

17、d source .6 9.4 Microphone and test sound source location in the test space .7 9.5 Sound incidence angles .7 10 Measurement of windscreen insertion loss in a reverberation room having an approximately diffuse test sound field 9 10.1 Test room and configuration 9 10.2 Test signals 9 10.3 Test sound a

18、nd room ambient noise level .9 10.4 Stationary microphone moved to different locations 9 10.5 Moving microphone . 10 11 Windscreen information to be reported . 10 11.1 Mechanical (physical) dimensions in millimeters to nearest 1/10 millimeter 10 11.2 Weight in grams to the nearest gram 11 11.3 Poros

19、ity . 11 11.4 Test conditions 11 11.5 Description of the specific test procedure used 11 11.6 Insertion loss nomenclature in each one-third-octave band for the average of three specimens . 11 11.7 Test instrumentation and test environment 11 11.8 Description of the instrument or device on which the

20、windscreen is mounted . 12 11.9 Sound field with no windscreen 12 11.10 Insertion loss values formatted for each windscreen according to Clause 11.6. 12 Annex A (informative) Information about microphone windscreens . 13 Annex B (informative) Uncertainty of windscreen insertion-loss measurements . 1

21、4 Annex C (informative) Data related to the uncertainty of windscreen insertion loss measured in reverberation rooms . 19 2014 Acoustical Society of America All rights reserved ii Tables Table B.1 Illustration of the calculation of the expanded uncertainty for a measurement of windscreen insertion l

22、oss at 1 kHz for tests conducted in a free-field test facility 18 Table C.1 Estimated expanded uncertainties with approximately 95% level of confidence for windscreen insertion loss measured in reverberation rooms . 20 iii 2014 Acoustical Society of America All rights reserved Foreword This Foreword

23、 is for information only and is not a part of the American National Standard ANSI/ASA S1.17-2014/Part 1 American National Standard Microphone Windscreens Part 1: Test Procedures for Measurements of Insertion Loss in Still Air. This standard comprises a part of a group of definitions, standards, and

24、specifications for use in acoustics. It was developed and approved by Accredited Standards Committee S1 Acoustics, under its approved operating procedures. Those procedures have been accredited by the American National Standards Institute (ANSI). The Scope of Accredited Standards Committee S1 is as

25、follows: Standards, specifications, methods of measurement and test, and terminology in the field of physical acoustics, including architectural acoustics, electroacoustics, sonics and ultrasonics, and underwater sound, but excluding those aspects which pertain to biological safety, tolerances, and

26、comfort. This standard is a revision of ANSI S1.17-2004/Part 1, which has been technically and editorially revised. This standard is not comparable to any existing IEC or ISO standard. This standard includes three informative annexes. At the time this standard was submitted to Accredited Standards C

27、ommittee S1, Acoustics, for approval, the membership was as follows: P. Battenberg, Chair R.J. Peppin, Vice-Chair S.B. Blaeser, Secretary Acoustical Society of America . A.H. Marsh P.D. Schomer (Alt.) Air-Conditioning, Heating and Refrigeration Institute S. Lind . D. Abbate (Alt.) American Industria

28、l Hygiene Association. D. Driscoll .D. Sandfort (Alt.) Campanella Associates. A.J. Campanella Casella USA R. Selwyn . R. Brauch (Alt.) ETS-Lindgren Acoustic Systems D. Winker . M. Black (Alt.) G.R.A.S. Sound FAX: 1 631-390-0217; E-mail: asastdsaip.org. v 2014 Acoustical Society of America All rights

29、 reserved Introduction Windscreens are commonly placed around microphones for measurements of sound pressure levels at outdoor and indoor locations in conditions with moving air. Windscreens are also used to protect a microphone from harsh environmental conditions, such as from dust, rain, or possib

30、le mechanical contact with any object. The measurement of a sound with a windscreen over the microphone in moving air yields a result with less total uncertainty than a measurement without the windscreen around the microphone. As a goal, the measurement of a sound without a windscreen and without mo

31、ving air would be close to the measurement of the same sound with a windscreen installed and in air moving at any speed. Practically, the measurement of a sound in moving air with a windscreen over a microphone yields a result with less of the influence of the airflow-induced turbulence near the mic

32、rophone than would be present if the windscreen were not installed. Windscreens introduce some high frequency insertion loss, dependent on windscreen structure and material, and a small amount of diffraction gain at mid-frequencies. This will affect the frequency characteristic of a measurement inst

33、rument. The purpose of this Part 1 is to describe procedures to determine this insertion loss (ANSI/ASA S1.1-2013, 6.71) of a windscreen mounted on a microphone located in still air or moving slowly along a path in still air. AMERICAN NATIONAL STANDARD ANSI/ASA S1.17-2014/Part 1 2014 Acoustical Soci

34、ety of America All rights reserved 1 American National Standard Microphone Windscreens Part 1: Test Procedures for Measurements of Insertion Loss in Still Air 1 Scope 1.1 Part 1 of this standard describes alternative methods for determining the insertion loss of a windscreen placed around a specifie

35、d stationary microphone in still air or moving slowly along a path in still air. The insertion loss is determined by measuring the sound pressure level without and with the windscreen around the microphone. The insertion loss is measured either in anechoic space or in a reverberation room. The measu

36、red insertion loss is the result of the characteristics of the windscreen including sound absorption, sound insulation and sound diffraction properties of the windscreen material, and from sound diffraction effects of the windscreen size, shape and construction details. NOTE Although measurements of

37、 insertion loss of a windscreen in still air do not characterize the acoustical performance of the windscreen in moving air, they do provide an indication of the effect of a windscreen at wind speeds approaching zero on the level of the sound pressure at the microphone as modified by the presence of

38、 that windscreen. 1.2 This standard applies to any kind or shape of windscreen made from any kind of porous material and intended to be placed around a measurement microphone to reduce the influence of moving air on the sound pressure at the microphone, or to provide protection from dust and other p

39、articles in the air. Other windscreen properties are cited in Annex A. This standard also applies to porous “nose cones“ placed around a microphone in a flow of air or other gas. 1.3 Insertion loss is measured in an anechoic room for applications where it is important to know the effect of a windscr

40、een on a microphones directional response as well as the effect on the acoustical sensitivity of a measurement system. Insertion loss is measured in the diffuse field of a reverberation room for applications where sound arrives at a microphone from random directions. 1.4 This standard describes meth

41、ods for determining the insertion loss of a windscreen over a frequency range selected by the user as applicable to an intended measurement of the sound pressure level at a point in a sound field. The measured insertion losses may be used to classify windscreens according to their physical propertie

42、s. The measured insertion losses may also be useful for estimating the sound pressure levels that would have been measured in the absence of a windscreen. Annex A provides general information about microphone windscreens.1 2 Normative references The following referenced documents are indispensable f

43、or the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ANSI/ASA S1.1-2013, American National Standard Acoustical Terminology ANSI/ASA S1.40-2006 (R 2011), Ame

44、rican National Standard Specifications and Verification Procedures for Sound Calibrators 1 The Bibliography contains a list of references with information about the design and testing of microphone windscreens. ANSI/ASA S1.17-2014/Part 1 2014 Acoustical Society of America All rights reserved 2 ANSI/

45、ASA S12.51-2012 / ISO 3741:2010, American National Standard Acoustics Determination of Sound Power Levels and Sound Energy Levels of Noise Sources Using Sound Pressure Precision Methods for Reverberation Test Rooms (a nationally adopted international standard) ANSI/ASA S12.55-2012 / ISO 3745:2012, A

46、merican National Standard Acoustics Determination of Sound Power Levels and Sound Energy Levels of Noise Sources Using Sound Pressure Precision Methods for Anechoic and Hemi-Anechoic Rooms (a nationally adopted international standard) IEC 60942:2003, ed. 3.0, Electroacoustics Sound calibrators IEC 6

47、1260:1995, Electroacoustics Octave-band and fractional octave-band filters, including Amendment 1:2001 ISO/IEC Guide 98-3:2008, Uncertainty of measurement Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) 3 Terms and definitions For the purposes of this Part 1, the following d

48、efinitions apply. Definitions for related quantities are given in ANSI/ASA S1.1. 3.1 windscreen device placed around a microphone to reduce the influence of airflow and the turbulent-flow-generated sound at the microphone NOTE For a bare microphone, wind-generated turbulence is at the grid cover edg

49、es immediately adjacent to the diaphragm and can comprise intense sound. When a windscreen is fitted over the microphone, the wind-generated turbulence is at the larger contour of the windscreen surface and is less intense. Since this surface is also more distant from the microphone, its sound level at the microphone is accordingly much less intense. Auxiliary components such as a rain-hat or bird spikes used in service may be attached to the windscreen under test. 3.2 free field field in a homogeneous medium free from boundaries. In p