ASA S12 6-2016 American National Standard Methods for Measuring the Real-Ear Attenuation of Hearing Protectors.pdf

1、 ANSI/ASA S12.6-2016 AMERICAN NATIONAL STANDARD Methods for Measuring the Real-Ear Attenuation of Hearing Protectors Accredited Standards Committee S12, Noise Standards Secretariat Acoustical Society of America 1305 Walt Whitman Road, Suite 300 Melville, NY 11747 ANSI/ASAS12.6-2016The American Natio

2、nal 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 America (ASA) is an organization of scientists and engineers formed in 1929 to in

3、crease and diffuse the knowledge of acoustics and to promote its practical applications. ANSI/ASA S12.6-2016 (Revision of ANSI/ASA S12.6-2008) AMERICAN NATIONAL STANDARD Methods for Measuring the Real-Ear Attenuation of Hearing Protectors Secretariat: Acoustical Society of America Approved on June 1

4、6, 2016 by: American National Standards Institute, Inc. Abstract This standard specifies laboratory-based procedures for measuring, analyzing, and reporting the passive noise-reducing capabilities of hearing protectors. The procedures consist of psychophysical tests conducted on human subjects to de

5、termine the real-ear attenuation measured at hearing threshold. Two fitting procedures are provided: Method A) trained-subject fit, intended to describe the capabilities of the devices fitted by carefully trained users, and Method B) inexperienced-subject fit, utilizes subjects with little or no exp

6、erience with respect to the use of hearing protection, in order to approximate the attenuation that can be attained by groups of users as reported in real-world occupational studies. Regardless of test method, the attenuation data will be valid only to the extent that the users wear the devices in t

7、he same manner as during the tests. This standard does not address issues pertaining to computational schemes or rating systems for applying hearing protector attenuation values (see ANSI/ASA S12.68), nor does it specify minimum performance values for hearing protectors, or address comfort or wearab

8、ility features. Method A of this standard corresponds to ISO 4869-1:1990, Acoustics Hearing protectors Part 1: Subjective method for the measurement of sound attenuation, and Method B corresponds to ISO/TS 4869-5:2006, Acoustics Hearing protectors Part 5: Method for estimation of noise reduction usi

9、ng fitting by inexperienced test subjects. AMERICAN NATIONAL 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/SC1 on Animal Bioacoustics, and S12 o

10、n 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 published by the Acoustical Society of America as American National Standards after

11、 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, industry, and consumers, and to Federal, State, and local governments. Each of the Accre

12、dited 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 Committee organization and activity and provides liaison between the Accredited S

13、tandards 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 their publication and distribution. An American National Standard implies a consens

14、us 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 affected interests. Substantial agreement means much more than a simple majority,

15、 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 voluntary. Their existence does not in any respect preclude anyone, whether he or she ha

16、s 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 withdrawn at any time. The procedures of the American National Standards Institute requir

17、e that action be taken periodically to reaffirm, revise, or withdraw this standard. Acoustical Society of America ASA Secretariat 1305 Walt Whitman Road, Suite 300 Melville, New York 11747-4300 Telephone: 1 (631) 390-0215 Fax: 1 (631) 923-2875 E-mail: asastdsacousticalsociety.org 2016 by Acoustical

18、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 written permission of the publisher. For permission, address a req

19、uest to the Standards Secretariat of the Acoustical Society of America.ANSI/ASA S12.6-2016 2016 Acoustical Society of America All rights reserved iContents 1 Scope . 1 1.1 Scope . 1 1.2 Applications . 1 2 Normative references . 2 3 Terms and definitions . 3 4 Physical requirements of the test facili

20、ty 4 4.1 Test signals 4 4.2 Test site . 4 4.3 Test apparatus . 5 4.4 Head position reference device . 7 4.5 Observation of subjects during testing 7 5 Test subjects 7 5.1 Anatomical features . 7 5.2 Otoscopic inspection . 8 5.3 Measurement of earcanal size and head dimensions . 8 5.4 Gender balance

21、. 8 5.5 Hearing sensitivity . 8 5.6 Threshold variability (during qualification) . 8 5.7 Eyeglasses and jewelry . 9 5.8 Number and method of selection of subjects 9 6 Product samples. 9 6.1 Minimum number of samples 9 6.2 Earplugs connected via a flexible retaining cord . 9 6.3 Devices with variable

22、 band force adjustments 10 6.4 Special requirements for inexperienced-subject-fit method 10 7 Psychophysical procedure . 10 7.1 Informing the subject . 10 7.2 Positioning the subject . 10 7.3 Number of open and occluded threshold measurements . 10 7.4 Threshold measurement method - Bksy tracking pro

23、cedure 11 7.5 Threshold sensitivity at time of testing 11 7.6 Open threshold variability within a test session . 11 7.7 Quiet period prior to first threshold measurement . 11 7.8 Waiting period subsequent to fitting hearing protector 11 8 Method A: Trained-subject fit . 12 8.1 Training in fitting he

24、aring protectors 12 8.2 Conditions for subject dismissal 12 8.3 Test procedures . 12 9 Method B: Inexperienced-subject fit . 13 9.1 Conditions for subject acceptance/dismissal . 13 9.2 Test preparation. 14 9.3 Test procedure. 16 ANSI/ASA S12.6-2016 2016 Acoustical Society of America All rights reser

25、ved ii 10 Band force 16 10.1 Earmuffs . 17 10.2 Semi-insert devices 17 11 Processing and reporting the data . 17 11.1 Recording the data . 17 11.2 Computation of real-ear attenuation . 17 11.3 Estimation of the uncertainty and procedures for assuring laboratory conformity . 18 11.4 Information to be

26、 included in test report . 18 11.5 Graphical presentation of the data . 19 Annex A (informative) Uncertainty of hearing protector attenuation measurements . 20 A.1 General . 20 A.2 Uncertainty within a laboratory 21 A.2.1 Application of the expanded uncertainty 22 A.2.2 An example . 22 A.3 Uncertain

27、ties between laboratories. 23 A.3.1 Application of the expanded uncertainty 24 Annex B (normative) Procedure for measuring earcanal sizes and head dimensions 25 Annex C (informative) Checklist for implementing Methods A and B 27 Annex D (normative) Procedure for measurement of the band force of semi

28、-insert devices 29 Annex E (normative if accreditation is sought) Requirements for accreditation 32 Bibliography . 35 Figures Figure B.1 Dimensions o f a tool to size earcanals . 25 Figure B.2 Bi tragion width . 26 Figure B.3 Head height . 26 Figure D.1 Semi-insert pinna adapter dimension definition

29、s 30 Figure D.2 Rigid base plate s uitable for pinna adapter 31 Tables Table 1 Allowable variation of sound-field sound pressure levels within each plane, for corresponding directional microphone free-field rejection . 5 Table 2 Maximum permissible am bient noise at the reference point . 6 Table A.1

30、 General form of an uncertainty budget for hearing protector determinations 21 ANSI/ASA S12.6-2016 2016 Acoustical Society of America All rights reserved iiiTable A.2 Estimates of Method-A within-laboratory uncertainty for the mean attenuation 22 Table A.3 An example of Method-A earmuff test data in

31、 decibels for a given laboratory 23 Table A.4 Estimates of Method-A between-laboratory uncertainty for the mean attenuation 23 Table D.1 Pinna dimensions for force measurements of semi-insert devices, from ANSI/ASA S3.36-2012, Table D.1 . 29 ANSI/ASA S12.6-2016 2016 Acoustical Society of America All

32、 rights reserved iv Foreword This Foreword is for information only and is not a part of the American National Standard ANSI/ASA S12.6-2016 American National Standard Methods for Measuring the Real-Ear Attenuation of Hearing Protectors (revision of ANSI/ASA S12.6-2008). As such, this Foreword may con

33、tain 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 and a

34、pproved 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 the f

35、ield 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 revision of ANSI/ASA S12.6-2008. The principal changes in this up

36、date pertain to the definition of the filters used in signal generation, room ambient noise requirements and various other items regarding the test site as described in Clause 4, retention of subjects during Method-B testing, a completely revised annex on the computation of uncertainty in close harm

37、onization with the related specifications in ISO 4869-1, and inclusion of requirements on laboratory procedures for purposes of accreditation for laboratories choosing to become accredited. This standard is comparable to two existing ISO standards. Method A corresponds to ISO 4869-1:1990, Acoustics

38、Hearing protectors Part 1: Subjective method for the measurement of sound attenuation, with the principal differences being in the number of test subjects and replications, the fitting instructions, and certain details of the electroacoustic test specifications, especially the room ambient noise. Me

39、thod B corresponds to ISO/TS 4869-5:2006, Acoustics Hearing protectors Part 5: Method for estimation of noise reduction using fitting by inexperienced test subjects, again with similar differences as between Method A and 4869-1. This standard does not include performance requirements for hearing pro

40、tectors, nor does it specify how to use the attenuation values derived from testing via the methods of this standard for the prediction of protected noise exposures; computational methods and attenuation ratings are described in ANSI/ASA S12.68-2008 (R2012). This standard also does not pertain to ph

41、ysical attenuation measurements using acoustical test fixtures or microphones mounted in human earcanals; those procedures are covered in ANSI/ASA S12.42-2010. And finally, with respect to attenuation obtained by individual users, a standard is under development that will provide specifications for

42、field attenuation estimation systems (FAES) intended to estimate the personal attenuation ratings of hearing protection devices obtained by individual wearers in actual practice (BSR/ASA S12.71-201X). At the time this standard was submitted to Accredited Standards Committee S12, Noise for approval,

43、the membership was as follows: S.J. Lind, Chair D.F. Winker, Vice-Chair S.B. Blaeser, Secretary 3M Personal Safety Division . E. H. Berger Acoustical Society of America . R.D. Hellweg D. Lubman (Alt.) ANSI/ASA S12.6-2016 2016 Acoustical Society of America All rights reserved vAir-Conditioning and Re

44、frigeration Institute S. Lind D. Abbate (Alt.) American Academy of Audiology . T. Ricketts C. Schweitzer (Alt.) American Academy of Otolaryngology R.A. Dobie . A. Kim (Alt.) American Industrial Hygiene Association . D. Driscoll M. Kram (Alt.) American Speech-Language-Hearing Association . L.A. Wilbe

45、r N. DiSarno (Alt.) Boeing Commercial Airplanes, Noise, Vibration Fax: 631-923-2875; E-mail: asastdsacousticalsociety.org. ANSI/ASA S12.6-2016 2016 Acoustical Society of America All rights reserved viii Introduction This standard describes real-ear attenuation at threshold (REAT) methods for the mea

46、surement of the noise attenuation of hearing protection devices (HPDs). Variations of this approach have been in wide use since the development of ASA Z24.22-1957. REAT data have generally been recognized as yielding the best measure of the noise attenuation provided by passive hearing protection de

47、vices and include the effects of sound transmission from flanking pathways, such as those arising from tissue and bone conduction (Berger, 1986). Key factors influencing the measured attenuation values are the selection, training, and fitting of the hearing protector test subjects. For that reason t

48、his standard includes two methods with distinctly differing approaches for dealing with these issues. Method A, previously called “experimenter-supervised fit” and now designated “trained-subject fit,” describes something close to an optimum fitting scenario that can be accomplished by a motivated a

49、nd proficient user. It allows full training and intervention by the experimenter prior to the attenuation measurement, but for the actual test the subject must don the hearing protector on his or her own without assistance. The rationale is that allowing intensive individualized training immediately prior to a subject fitting the device is a reasonable reflection of the best that can be obtained in practice. The reason to preclude the experimenter from actually fitting the device was the observation that experimenters, wh