1、PD ISO/PAS 20065:2016 Acoustics Objective method for assessing the audibility of tones in noise Engineering method BSI Standards Publication WB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06PD ISO/PAS 20065:2016 PUBLISHED DOCUMENT National foreword This Published Document is the UK implementa
2、tion of ISO/PAS 20065:2016. The UK participation in its preparation was entrusted to Technical Committee EH/1, Acoustics. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a
3、contract. Users are responsible for its correct application. The British Standards Institution 2016. Published by BSI Standards Limited 2016 ISBN 978 0 580 93282 3 ICS 17.140.01 Compliance with a British Standard cannot confer immunity from legal obligations. This Published Document was published un
4、der the authority of the Standards Policy and Strategy Committee on 31 July 2016. Amendments issued since publication Date Text affectedPD ISO/PAS 20065:2016 ISO 2016 Acoustics Objective method for assessing the audibility of tones in noise Engineering method Acoustique Mthode objective pour valuer
5、laudibilit des tons dans le bruit Mthode dexpertise PUBLICLY AVAILABLE SPECIFICATION ISO/PAS 20065 First edition 2016-0 7-01 Reference number ISO/PAS 20065:2016(E)PD ISO/PAS 20065:2016ISO/PAS 20065:2016(E)ii ISO 2016 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in Switzerland
6、 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requeste
7、d from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyrightiso.org www.iso.orgPD ISO/PAS 20065:2016ISO/PAS 20065:2016(E)Foreword i
8、v 1 Scope . 1 2 Normative references 1 3 T erms and definitions . 1 4 Measurement procedure 5 4.1 General . 5 4.2 Measurement instruments . 5 4.3 Merging the basic spectra 5 5 Evaluation 6 5.1 General information . 6 5.2 Width f cof the critical band . 7 5.3 Determination of prominent tones 7 5.3.1
9、General information 7 5.3.2 Determination of the mean narrow-band level L Sof the masking noise 7 5.3.3 Determination of the tone level L Tof a tone in a critical band 8 5.3.4 Distinctness of a tone . 9 5.3.5 Determination of the critical band level, L G , of the masking noise 10 5.3.6 Masking index
10、 .10 5.3.7 Determination of the audibility, L .10 5.3.8 Determination of the decisive audibility, L j , of a narrow-band spectrum 10 5.3.9 Determination of the mean audibility L of a number of spectra 12 6 Calculation of the unc ertainty of the audibility L 13 7 Recommendations on the presentation o
11、f results .16 7.1 Measurement .16 7.2 Acoustic environment 16 7.3 Instruments for measurement, recording and evaluation .16 7.4 Acoustic data 16 Annex A (informative) Window effect and Picket fence effect 17 Annex B (informative) Resolving power of the human ear at frequencies below 1 000 Hz and geo
12、metric position of the critical bands corner frequencies .20 Annex C (informative) Masking, masking threshold, masking index 22 Annex D (informative) It er ati v e method for the det ermination of the audibility , L .23 Annex E (informative) Example for the determination of the tonal audibility .27
13、Bibliography .33 ISO 2016 All rights reserved iii Contents PagePD ISO/PAS 20065:2016ISO/PAS 20065:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is nor
14、mally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in
15、the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular t
16、he different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this doc
17、ument may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.o
18、rg/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement. For an explanation on the meaning of ISO specific terms and expressions related to conformit y assessment, as well as information about ISOs adherence to the Wo
19、rld Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html. The committee responsible for this document is ISO/TC 43, Acoustics, Subcommittee SC 1, Noise.iv ISO 2016 All rights reservedPD ISO/PAS 20065:2016PUBLICLY AVAILABLE
20、SPECIFICATION ISO/PAS 20065:2016(E) Acoustics Objective method for assessing the audibility of tones in noise Engineering method 1 Scope This Publicly Available Specification describes a method for the objective determination of the audibility of tones in environmental noise. This Publicly Available
21、 Specification is intended to augment the usual method for evaluation on the basis of aural impression, in particular, in cases in which there is no agreement on the degree of the audibility of tones. The method described can be used if the frequency of the tone being evaluated is equal to, or great
22、er than, 50 Hz. In other cases, if the tone frequency is below 50 Hz, or if other types of noise (such as screeching) are to be captured, then this method cannot replace subjective evaluation. The method presented herein can be used in continuous measurement stations that work automatically. 2 Norma
23、tive references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments)
24、applies. ISO 1996-1, Acoustics Description, measurement and assessment of environmental noise Part 1: Basic quantities and assessment procedures IEC 61672-1, Electroacoustics Sound level meters Part 1: Specifications 3 T erms a nd definiti ons For the purposes of this document, the terms and definit
25、ions given in ISO 1996-1 and the following apply. 3.1 tonality presence of a tone in a noise, the level of which is below that of the remaining noise components in the critical band (3.5) about the tone frequency (3.2) by less than the value of the masking index (3.16), a v 3.2 tone frequency f T fr
26、equency of the spectral line (3.23) (or mid-band frequency of the narrow-band filter), to the level of which the tone contributes most strongly 3.3 tone level L T energy summation of the narrow-band level (3.22) with the tone frequency (3.2), f T , and the lateral lines about f T , assignable to thi
27、s tone Note 1 to entry: If the critical band (3.5) for the frequency, f T , under consideration contains a number of tones, then the tone level, L T , is the energy sum of these tones. This level, L T , is then assigned to the frequency of the participating tone that has the maximal value of audibil
28、ity (3.4), L. Note 2 to entry: The method for the determination of the tone level, L T , of a tone in a critical band is described in 5.3.3. ISO 2016 All rights reserved 1PD ISO/PAS 20065:2016ISO/PAS 20065:2016(E) 3.4 audibility L difference between the tone level (3.3), L T , and the masking thresh
29、old (3.15), L T Note 1 to entry: The method for the determination of the decisive audibility (3.24), L j , of a narrow-band spectrum (3.12) is described in 5.3.8. 3.5 critical band frequency band with a bandwidth (3.17), f c , within which the auditory system integrates the sound intensity in the fo
30、rmation of loudness and within which it integrates the sound intensity in the formation of the masking threshold (3.15) Note 1 to entry: This characteristic of a critical band (see also References 3 and 4) holds only for a restricted sound level range. This dependence is neglected here. 3.6 mean nar
31、row-band level of the critical band L S energy mean value of all narrow-band levels (3.22) in a critical band (3.5) that (as a rule) does not exceed this mean value by more than 6 dB Note 1 to entry: The method for the determination of the mean narrow-band level L Sof the masking noise is described
32、in 5.3.2 and Annex D (iterative method). 3.7 critical band level L G level of noise that is assigned to the critical band (3.5) that describes the masking characteristic of the noise for one or more tones of the noise in this critical band Note 1 to entry: See narrow-band level (3.22) and Annex C fo
33、r masking. Note 2 to entry: For the definition formula for L G , see Formula (12). 3.8 sampling frequency f S number of samples taken per second Note 1 to entry: The analogue data provided continuously are converted into samples through sampling at discrete time intervals for digital processing. Not
34、e 2 to entry: To ensure the reproducibility of a digitized signal, the Shannon theorem requires that the sampling frequency, f S , is at least 2 times the highest frequency of the signal components used for evaluation in the time signal f S 2 f N , see also aliasing (3.9), antialiasing filter (3.10)
35、 and useable frequency (3.20). The algorithm of a Fast Fourier Transform analysis (the variant of a discrete Fourier Transform used typically and optimized for calculation) only permits block lengths (3.11), N, that correspond to a power of two. FFT analyzers thus need a sampling frequency that is a
36、t least 2,56 times the maximum frequency to be analysed. 3.9 aliasing reflection in the line spectrum (3.12) of frequency components from the range above the sampling frequency (3.8) divided by two ( f S /2) in the range below f S /2 Note 1 to entry: Antialiasing filters (3.10) are used to avoid err
37、ors through such reflections. Note 2 to entry: Half the sampling frequency ( f S /2) is also known as the Nyquist frequency.2 ISO 2016 All rights reservedPD ISO/PAS 20065:2016ISO/PAS 20065:2016(E) 3.10 a n t ia lia sing f i l t e r l ow- p a s s f i l t e r ideal filter that allow frequencies below
38、half the sampling frequency (3.8) to pass through completely (without influencing the signal), but completely block all higher frequencies Note 1 to entry: To prevent aliasing (3.9), the noise under investigation shall be filtered using an antialiasing filter before analogue-to-digital conversion. N
39、ote 2 to entry: Real aliasing filters have a final damping (generally 120 dB/octave) within the blocking range, i.e. signal components in this transition range are reflected (damped). For example, in the transformation of 2 048 (2 k) data points, 1 024 frequency lines are calculated and 800 lines sh
40、own. A component in the line number 1 248 is folded back into the line number 800. With a low-pass filter of 120 dB/octave the damping of these components is approximately 75 dB. Note 3 to entry: The usual commercial FFT analyzers have an antialiasing filter, the limit frequency of which can be swit
41、ched automatically with the selectable sampling frequency. The reflection of simulated narrow-band levels (3.22) is suppressed. 3.11 block length N block of sampling values that in discrete form represents a time-limited range of the time signal to be analysed Note 1 to entry: In contrast to frequen
42、cy analysis with analogue and digital filters, the noise with the Fast Fourier Transform is processed in data blocks. In general, these blocks embrace only a part of the noise recording. The block length, N, expresses the number of data points processed at the same time. Due to the nature of the Fas
43、t Fourier Transform, the value of N has the integer of power of 2. It has a value, for example, of N = 2 10= 1 024 data points. 3.12 line spectrum narrow-band spectrum frequency spectrum plot of the sound pressure level (narrow-band level) (3.22) as a function of the frequency in frequency bands of
44、constant bandwidth (3.17) (line spacing, f ) (3.13) Note 1 to entry: A-weighting of the level is assumed in this Publicly Available Specification. Note 2 to entry: Frequency analysis delivers a line spectrum, in which each line represents the output of a filter, the mid-frequency of which correspond
45、s to the frequency of the spectral line (3.23). 3.13 line spacing frequency resolution distance between neighbouring spectral lines (3.23), where the line spacing in the FFT is given by wheref S is the sampling frequency (3.8);N is the block length (3.11). Note 1 to entry: In this Publicly Available
46、 Specification, the line spacing is 1,9 Hz f 4,0 Hz. ISO 2016 All rights reserved 3PD ISO/PAS 20065:2016ISO/PAS 20065:2016(E) 3.14 time window time data set of the signal segment (block length) (3.11) that is multiplied by a weighting function (window function) Note 1 to entry: In accordance with th
47、e definition of the Fourier integral, a prerequisite of the FFT analysis is that the time data set is periodic. If this is not the case (as with stochastic signals), cut-off effects at the edges of the time window will lead to distortion of the spectrum. These distortions are avoided through weighti
48、ng functions such as the Hanning Function. Note 2 to entry: For more information on window and weighting functions, see, for example, Reference 5 and Annex A. 3.15 masking threshold L T audibility (3.4) threshold for a specific sound in the presence of a masking sound (masker) Note 1 to entry: See A
49、nnex C for more information on the audibility threshold and the masking noise. 3.16 masking index a v difference between the masking threshold (3.15), L T , and the critical band level (3.7), L G , of the masking noise Note 1 to entry: For frequency-dependent masking index, a v , masking and masking noise, see Annex C. 3.17 bandwidth frequency bandwidth frequency range of a number of neighbouring spectral lines (3.23) Note 1 to entry: If the width of a frequency band is calculated for w
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