© ISO 2016 Acoustics — Objective method for assessing the audibility of tones in noise — Engineering method Acoustique — Méthode objective pour évaluer l’audibilité des tons dans le bruit — Méthode d’[.]
PUBLICLY AVAILABLE SPECIFICATION ISO/PAS 20065 First edition 2016-0 7-01 Acoustics — Objective method for assessing the audibility of tones in noise — Engineering method Acoustique — Méthode objective pour évaluer l’audibilité des tons dans le bruit — Méthode d’expertise Reference number ISO/PAS 20065:2016(E) © ISO 2016 ISO/PAS 20065:2016(E) COPYRIGHT PROTECTED DOCUMENT © ISO 2016, Published in Switzerland All rights reserved Unless otherwise specified, no part o f 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 requested from either ISO at the address below or ISO’s member body in the country o f the requester ISO copyright o ffice Ch de Blandonnet • CP 401 CH-1214 Vernier, Geneva, Switzerland Tel +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org ii © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Contents Page Foreword iv Scope Normative references Terms and definitions Measurement procedure 4.1 General 4.2 Measurement instruments 4.3 Merging the basic spectra 5 Evaluation 5.1 General information fc of the critical band 5.3 Determination of prominent tones 5.3.1 General information 5.3.2 Determination of the mean narrow-band level LS of the masking noise 5.3.3 Determination of the tone level LT of a tone in a critical band 5.3.4 Distinctness of a tone 5.3.5 Determination of the critical band level, LG, of the masking noise 10 5.3.6 Masking index 10 f L f Lj, of a narrow-band spectrum 10 f L of a number of spectra 12 Calculation o f the uncertainty o f the audibility Δ L 13 Recommendations on the presentation of 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 000 Hz and geometric position of the critical bands — corner frequencies 20 Annex C (informative) Masking, masking threshold, masking index 22 Annex D (informative) Iterative method for the determination o f the audibility, ∆L 23 Annex E (informative) Example for the determination of the tonal audibility 27 Bibliography 33 Width Δ D eterminatio n o the audib ility, Δ D eterminatio n o the decis ive audib ility, Δ D eterminatio n o the mean audib ility Δ © ISO 2016 – All rights reserved iii ISO/PAS 20065:2016(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies) The work o f preparing International Standards is normally 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 the work ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters o f electrotechnical standardization The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part In particular the different approval criteria needed for the di fferent types o f ISO documents should be noted This document was dra fted in accordance with the editorial rules of the ISO/IEC Directives, Part (see www.iso.org/directives) Attention is drawn to the possibility that some o f the elements o f this document may be the subject o f patent rights ISO shall not be held responsible for identi fying any or all such patent rights Details o f any patent rights identified during the development o f the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents) Any trade name used in this document is in formation given for the convenience o f users and does not constitute an endorsement For an explanation on the meaning o f ISO specific terms and expressions related to formity assessment, as well as information about ISO’s adherence to the World 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 reserved PUBLICLY AVAILABLE SPECIFICATION ISO/PAS 20065:2016(E) Acoustics — Objective method for assessing the audibility of tones in noise — Engineering method Scope This Publicly Available Specification describes a method for the objective determination o f the audibility of tones in environmental noise This Publicly Available 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 o f tones The method described can be used i f the frequency o f the tone being evaluated is equal to, or greater than, 50 Hz In other cases, i f the tone frequency is below 50 Hz, or i f other types o f 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 Normative references The following documents, in whole or in part, are normatively re ferenced in this document and are indispensable for its application For dated re ferences, only the edition cited applies For undated re ferences, the latest edition o f the re ferenced document (including any amendments) 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 Terms and definitions For the purposes o f this document, the terms and definitions 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 o f the masking index (3.16), a v 3.2 tone frequency fT frequency o f the spectral line (3.23 ) (or mid-band frequency o f the narrow-band filter), to the level o f which the tone contributes most strongly 3.3 tone level LT energy summation o f the narrow-band level (3.22) with the tone frequency (3.2), fT, and the lateral lines about fT, assignable to this tone Note to entry: I f the critical band (3.5 ) for the frequency, fT, under consideration contains a number of tones, then the tone level, LT, is the energy sum of these tones This level, LT, is then assigned to the frequency of the participating tone that has the maximal value of audibility (3.4), Δ L Note to entry: The method for the determination o f the tone level, LT, of a tone in a critical band is described in 5.3.3 © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) 3.4 audibility Δ L difference between the tone level (3.3), LT, and the masking threshold (3.15), L T ′ fo r N o te to entr y: T he me tho d (3.12) is described in 5.3.8 3.5 critical band the de ter m i n ation o f the (3.17 formation of the masking threshold (3.15) fre quenc y i nten s ity b and with a in bandwidth formation the fc , ), ∆ o f loud ne s s and decisive audibility (3.24 ), Δ Lj , of a narrow-band spectrum with i n wh ich the aud itor y s ys tem i nte grate s the s ound with i n wh ich it i ntegrate s N o te to entr y: T h i s ch a rac teri s tic o f a c ritic a l b a nd (s e e a l s o Re ference s [ sound level range This dependence is neglected here the ] a nd [ s ou nd i nten s ity ] ) ho ld s o n l y for in the a re s tr ic te d 3.6 mean narrow-band level of the critical band LS energ y me an va lue o f a l l narrow-band levels (3.22) in a critical band (3.5) that (as a rule) does not exceed th i s me a n va lue by more th an dB N o te to entr y: T he me tho d for the de ter m i n atio n o f the me a n n a r row- b a nd le vel described in 5.3.2 and Annex D (iterative method) LS of the masking noise is 3.7 critical band level LG 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 N o te to entr y: S e e narrow-band level N o te to entr y: For the de fi n ition (3.22) and Annex C for masking f L G , see Formula (12) fo rmu l a or 3.8 sampling frequency fS number of samples taken per second N o te to entr y: T he a n a lo gue d ata p rovide d co nti nuo u s l y a re co nver te d i nto s a mp le s th rough s a mp l i ng at N o te to entr y: To en s u re the rep ro duc ib i l ity o f a d i giti z e d s ign a l , the S h a n no n the orem re qu i re s that the discrete time intervals for digital processing s a mp l i n g S fre quenc y, f i n the ti me s ign a l [ fS , i s at le a s t ti me s the h ighe s t ≥ , see also aliasing (3.9), fN fre quenc y o f the s ign a l comp o nents u s e d antialiasin g filter for e va lu ation (3.10) and useable frequency (3.20)] The a l gor ith m o f a Fa s t Fou r ier Tra n s for m a n a l ys i s (the va r i a nt o f a d i s c re te Fo u r ier Tra n s for m u s e d typ ic a l l y a nd o p ti m i z e d for c a lc u l ation) on l y p er m its thu s ne e d a s a mp l i ng 3.9 aliasing refle c tion i n the frequency (3.8 fre quenc y line spectrum ) d ivide d b y two ( N o te to entr y: Antialiasin g filters N o te to entr y: H a l f the s a mp l i ng block lengths (3.11), N , th at co r re s p o nd to a p ower o f two F F T a n a l yz ers th at i s at le a s t , ti me s the m a xi mu m (3.12 f f /2) in the range below fS/2 fS (3.10 ) o re quenc y comp onents fre quenc y from to b e a n a l ys e d the range ab ove the sampling ) a re u s e d to avoid errors th rou gh s uch re fle c tion s S fre quenc y ( f /2 ) i s a l s o known a s the N yqu i s t fre quenc y © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) 3.10 a n t i a l i a s i n g f i l t e r ideal filter that allow frequencies below hal f the sampling frequency (3.8 ) to pass through completely (without influencing the signal), but completely block all higher frequencies l o w - p a s s f i l t e r Note to entry: To prevent aliasing (3.9 ), the noise under investigation shall be filtered using an antialiasing filter be fore analogue-to-digital conversion Note 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 trans formation o f 048 (2 k) data points, 024 frequency lines are calculated and 800 lines shown A component in the line number 248 is folded back into the line number 800 With a low-pass filter o f 120 dB/octave the damping o f these components is approximately 75 dB Note to entry: The usual commercial FFT analyzers have an antialiasing filter, the limit frequency o f which can be switched automatically with the selectable sampling frequency The reflection o f 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 to entry: In contrast to frequency analysis with analogue and digital filters, the noise with the Fast Fourier Trans form 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 Fast Fourier Transform, the value of N has the integer of power of It has a value, for example, of N = 10 = 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 constant bandwidth (3.17) (line spacing, ∆ f) (3.13) Note to entry: A-weighting o f the level is assumed in this Publicly Available Specification Note to entry: Frequency analysis delivers a line spectrum, in which each line represents the output o f a filter, the mid- frequency o f which corresponds to the frequency o f 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 ∆f = fS / N where fS N is the sampling frequency (3.8); is the block length (3.11) Note to entry: In this Publicly Available Specification, the line spacing is 1,9 Hz ≤ Δ f ≤ 4,0 Hz © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) 3.14 time window time data set of the signal segment (block length) (3.11 (window function) ) th at i s mu ltipl ie d b y a weighti ng func tion N o te to entr y: I n accorda nce with the de fi n ition o f the Fou r ier i nte gra l , a p rere qu i s ite o f the F F T a n a l ys i s i s th at 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 weighting functions such as the Hanning Function f f f f 5] and Annex A N o te to entr y: Fo r more i n o r m ation on wi ndow a nd weighti ng 3.15 masking threshold LT ′ audibility (3.4 ) th re s hold N o te to entr y: S e e o r e xa mp le , Re erence [ a s p e ci fic s ound i n the pre s ence o f a ma s ki ng s ou nd (mas ker) Annex C f o r more i n for m atio n o n the aud ib i l ity th re s hold a nd the m a s ki n g no i s e 3.16 masking index av difference between the masking noise N o te to entr y: For for u nc tion s , s e e , masking threshold fre quenc y- dep endent (3.15), m a s ki ng i nde x, ′ LT , and the critical band level (3.7), LG , of the , masking and masking noise, see Annex C av 3.17 bandwidth fre quenc y b a ndwidth fre quenc y range o f a nu mb er o f neighb ou ri ng N o te to entr y: I f the width o f a fre quenc y b a nd spectral lines i s c a lc u l ate d for (3.23) wh ich its b e gi n n i n g or end e s no t cor re s p ond to the b o u nd a r y b e twe en two s p e c tra l l i ne s , then on l y the s p e c tra l l i ne s th at l ie i n thei r c a lc u l ate d fre quenc y nge a re a s s igne d to the fre quenc y fu l l width with i n the b a nd 3.18 distinctness clarity ratio of the conspicuousness of a tone based on a bandpass noise to the conspicuousness of a sinusoidal tone of the same tone frequency (3.2), fT, and same tone level (3.3), LT 3.19 edge steepness ratio of the level difference between the maximum narrow-band level (3.22) of a tone, LTmax, and the na rrow-b and level s o f the fi rs t l i ne b elow/ab ove the tone to the corre s p ond i ng fre quenc y d i fference 3.20 useable frequency fN upp er l i m it fre quenc y o f the s igna l comp onents u s e d for eva luation 3.21 investigation range range within which tones are investigated in the line spectrum (3.12) 3.22 narrow-band level averaged level within a spectral line (3.23) © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) 3.23 spectral line frequency band o f bandwidth (3.17 ), ∆ f (line spacing) (3.13), in a line spectrum (3.12) 3.24 decisive audibility Δ Lj maximum audibility (3.4), ∆ L , in the individual spectrum, j Measurement procedure 4.1 General The measurement procedure will depend on the aims The requirements for the measurement and assessment procedure in terms of the choice of measurement point, measurement time and duration of measurement, extraneous noise, etc shall be satisfied The variable for determination o f audibility o f prominent tones is the sound pressure p (t) For frequency analysis, the A-weighted equivalent continuous sound pressure level, L Aeq , as given in ISO 1996-1, is to be established for the respective spectral lines If the spectrum is unweighted (linear), then it shall be corrected to A-weighting in accordance with IEC 61672-1 4.2 Measurement instruments Sound level meters that meet, or exceed, the requirements of Class in IEC 61672-1 shall be used These have a frequency weighting “A”/“LIN” or “A”/“Z” with a lower limit frequency equal to, or below, 20 Hz Additional instruments such as recording instruments (digital or magnetic tape) may also be used The measured values derived through recording instruments shall lie within the tolerance range given in IEC 61672-1 Analysis o f frequency components in the measurement signals is per formed using a frequency analyzer The constant line spacing, Δ f, shall lie in the range 1,9 Hz to Hz (inclusive) The use of the Hanning window is mandatory in this Publicly Available Specification For further processing, it shall be ensured that the digitalization o f the sound pressure signal across the entire dynamic range used has a resolution of at least 0,1 dB Before it is processed further, the analogue measurement signal shall be passed through a steep lowpass filter (antialiasing filter) to avoid errors in frequency analysis The sampling frequency (see 3.8) shall be at least two times the maximum usable frequency present (see 3.20) The Hanning window is to be used as time window to reduce lateral bands (see 3.14) 4.3 Merging the basic spectra The spectra for the prominent tone assessment shall have an averaging time o f approximately s Due to the line spacing of 1,9 Hz to Hz (see 4.2 ) and the typical frequency range, f, of a few kHz, the basic spectra given by the frequency analyzer will have an averaging time below s To get the averaging time o f approximately s, a number o f basic spectra shall be merged This shall be done line by line with Formula (1): © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Li where L i, j N 1 = 10 lg N ? N ∑ j =1 10 , Li , j / dB dB (1) is the level of the th spectral line for the th spectrum; is the number of merged spectra i j Evaluation 5.1 General information The aim o f evaluation is to establish the audibility, Δ L The procedure is the same for stationary and non-stationary noises For tones that can only just be perceived, a quaver (eighth note) is to be adopted as a base time that is adequate for hearing However, comprehensive studies have shown that the lower limit for use o f the procedure is reached at averaging times o f approximately s Lower averaging times lead to unjustified values o f audibility, Δ L (too high, but also too low) Signals that have a very high level dynamic and/or frequency dynamic that no longer correspond with a 3-second averaging can, there fore, not be evaluated using this Publicly Available Specification The following conditions shall be satisfied for the measurements — The extended uncertainty, U, o f the audibility, Δ L , with a coverage probability o f 90 % in a bilateral confidence interval (see Clause ) shall not exceed ±1,5 dB This is generally the case with evaluation of at least 12 time-staggered narrow-band averaged spectra If there are less than 12 averaged spectra then the uncertainty shall be taken into consideration as given in Clause — Where there are alternating operating states, all o f the operating states shall be covered by the averaging spectra used (see Annex E) Tonal components in di fferent critical bands are evaluated separately To arrive at a decision on whether a tonal audibility has to be made, only the most pronounced tone is considered I f a number o f tones are present within a critical band, then an energy summation o f their tone levels, LT , is carried out to yield a tone level, LT (see 5.3.8) A tonal audibility is per formed for a tone only i f its distinctness (see 3.18 ) is at least 70 % This means a maximal bandwidth, Δ fR, dependent on the tone frequency [see Formula (9)] and necessitates edge i steepness (see 3.19) of at least 24 dB/octave NOTE For the distinctness of a tone, see 5.3.4 NOTE Harmonic multiples o f a tone are evaluated, independently o f that tone, similarly to all other components of the spectrum A sample program to determine audibility can be downloaded from http://standards.iso.org/iso/20065 © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Annex B (informative) Resolving power of the human ear at frequencies below 000 Hz and geometric position of the critical bands — corner frequencies At a frequency below 000 Hz, i f there are several tones in a critical band, the human ear is able to distinguish between differences in the tone frequencies that are lower than the half width of the critical points or dashed lines in Figure B.1 band I f the critical band has two or more tones, then the ear can detect di fferences as shown by the Key — critical bandwidth as a function o f frequency[4] ··· noise that comprises two tones - noise that comprises more than two tones in the critical band under consideration requency, in Hertz (Hz) fD frequency di fference, in Hertz (Hz) f f Figure B.1 — Frequency differences between the tones of complex noises that the human ear can still resolve[6] 20 © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Two tones of tone frequencies, fT1 and fT2 , are evaluated separately i f both tone frequencies lie below 000 Hz and the frequency di fference, fD : fD = fT − fT (B.1) where , fT1 fT2 < 000 Hz Formula (B.1) exceeds the following value: fD = f / Hz , lg T 212 21 × 10 ,8 Hz (B.2) where 50 Hz < fT < 000 Hz; is the frequency o f the more pronounced tone, in Hertz (Hz) fT In this Publicly Available Specification, the critical band is modelled as an ideal rectangular filter with a mid- frequency, fT (tone frequency), the lower corner frequency, f1 , and the upper corner frequency, f2 , with these two corner frequencies having a geometric position to the tone frequency [see Re ferences [1],[2]; all frequencies in Hertz (Hz)] fT = f2 (B.3) f1 f2 (B.4) − f1 = ∆fc With the quadratic supplement, it follows from Formula (B.3) and Formula (B.4): f1 =− f2 = ∆fc f1 + ( ∆fc ) + fT2 + ∆fc © ISO 2016 – All rights reserved (B.5) (B.6) 21 ISO/PAS 20065:2016(E) Annex C (informative) Masking, masking threshold, masking index Masking is the raising o f the audibility threshold for a sound as a result o f the influence o f another sound [3] The masking threshold, L T , is that sound pressure level of a sinusoidal test tone that is required for it to be just perceivable in the presence o f a masking noise (critical band level, L G ) The masking threshold is ′ determined in repeated tests in which a group o f subjects with normal hearing can just perceive the tone in 50 % o f the cases The masking index, a v = L′T − LG , is the difference between the level of the test tone, L T , and the critical band level, LG At low frequencies, the masking index has a value o f approximately −2 dB Above a ′ transition range between 0,2 kHz and kHz, it falls at a constant logarithmic rate to −6 dB at 20 kHz Figure C.1 — Masking index, av, as a function of frequency, f The masking index, a v, is given by Formula (C.1): f / Hz ,5 a v = −2 − lg + dB 502 (C.1) where f 22 is the frequency, in Hertz (Hz) © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Annex D (informative) I t e Figure D.1 r a t i v e m e t h o d f o r s hows an iterative me tho d t h for e d e t e r m i n a t i o n o f t h e a u d i b i l i t y , ∆ L c a lc u lation o f the tona l aud ibi l ity Figure D.1 — Iterative method © ISO 2016 – All rights reserved 23 ISO/PAS 20065:2016(E) Detailed diagram The mean narrow-band level, LS for all spectral lines (see Figure D.2) , a nd au xi l i ar y quantitie s to de term i ne the u ncer tai nty are c a lc u late d , Figure D.2 — Detailed diagram 24 © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Detailed diagram The tone level, LT, and the auxiliary quantities to determine the uncertainty is calculated for the first/next spectral line o f frequency, fT In addition, the tone is checked for distinctness (see Figure D.3) [ , ] Figure D.3 — Detailed diagram Detailed diagram A number o f tones in one critical band are grouped together and auxiliary quantities for determination o f uncertainty are calculated The maximum Δ L o f the spectrum is identified (see Figure D.4) © ISO 2016 – All rights reserved 25 ISO/PAS 20065:2016(E) reached? with 5.3.8? yes Figure D.4 — Detailed diagram 26 © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Annex E (informative) Example for the determination of the tonal audibility T he noi s e e xample s are derive d from Re ference [ 7] 80 dB 70 60 50 LA 40 30 20 10 0 200 100 300 f Hz 400 Key frequency, f in H ertz (H z) c width of the critical band with the run index, , in Hertz (Hz) line spacing independent from the run index, , in Hertz (Hz) Δf i i Δ fi i Ki L A numb er o f s p ectral lines with to ne energy o f the to ne with the run index, i A-weighted sound pressure level, in decibels (dB) NO TE T he s p e c tr u m conta i n s fu r ther ton a l co mp o nents b e yo nd the nge s hown Figure E.1 — Narrow band spectrum of a combustion engine (Spectrum of 5) T he u n i form noi s e o f a combu s tion engi ne was re corde d on a tap e mach i ne, then five na rrow-b a nd spectra were derived As stated in 5.1 , a lower nu mb er o f narrow-b and average d s p e c tra i s s u fficient , is lower than or equal to ±1,5 dB , in this case, has a value of ±1,38 dB (see below) i f the va lue o f the ex tende d uncer ta i nty, U, o f the me an aud ibi l ity, Δ L T he e xtende d u ncer tai nty, U, o f th i s aud ibi l ity, Δ L © ISO 2016 – All rights reserved 27 ISO/PAS 20065:2016(E) Step 1: Determination of the line spacing and range to be investigated Li ne s p aci ng: Δ f = 2,7 Hz T Step 2: Determination of the tone frequencies, fTj,k, of the tone level, LTj,k, of the mean narrowband level, LS j,k, and the audibilities, Δ Lj,k, for all spectra ( j is the run index of the spectrum, k is the run index of the tone frequency) Range i nve s tigate d: , H z ≤ f ≤ 676 , H z The mean narrow-band levels, S , of the masking noise are calculated in each case in accordance with 5.3.2 Formula (6)] in an iterative procedure from the narrow-band levels of the critical band about the tone frequencies, T The tone levels, T , are calculated in accordance with 5.3.3 Formula (8)] from the narrow-band levels that lie dB above the mean narrow-band level, S , and less than 10 dB f f f Table E.1 f f ) L j, k [s e e f L j, k [s e e j, k L b elow the narrow-b a nd level s o or the fi rs t o the tone j, k re quenc ie s T he s e level s are given, b y way o e xample, i n the five s p e c tra (the s p e c tru m with the gre ate s t de ci s ive aud ibi l ity, Δ L j Table E.1 — Frequencies fi and A-weighted narrow-band levels Li in the critical band with the centre frequency 137,3 Hz o f the first spectrum fi Li fi Li fi Li in Hz in dB in Hz in dB in Hz in dB 96,9 99,6 102,3 105,0 107,7 49,40 50,68 50,09 53,37 44,47 131,9 134,6 137,3 140,0 142,7 62,94 58,49 65,87 62,66 50,25 166,9 169,6 172,3 175,0 177,6 52,56 51,39 52,49 47,68 51,26 110,4 50,91 145,3 51,32 180,3 49,03 113,0 51,41 148,0 52,30 183,0 61,42 115,7 118,4 121,1 123,8 126,5 129,2 59,40 64,54 57,57 51,02 50,76 59,93 150,7 153,4 156,1 158,8 161,5 164,2 52,58 53,15 67,04 67,27 57,40 57,17 185,7 188,4 191,1 193,8 196,5 59,52 48,43 50,84 48,20 55,95 NOTE The values in bold represent the frequencies and narrow-band level that contribute to the tone levels, T , in the , and are thus the frequencies and narrow-band level that, in the iterative procedure, lie more than dB above the mean A-weighted narrow-band levels, S , and less than 10 dB below the narrow-band levels for the corresponding tone frequencies For the three tones, it follows that f T1 = 118,4 Hz: = 64,54 dB; S1 = 49,91 dB, f T2 = 137,3 Hz: = 65,87 dB; S2 = 49,22 dB, and f T3 = 158,8 Hz: = 67,27 dB; S3 = 49,90 dB L k c r i tic a l b a nd ab o ut the to ne with the g re ate s t aud ib i l i t y, Δ L L — the n a r ro w- b a nd le ve l at the to ne re que nc y, f L L — the n a r ro w- b a nd le ve l at the to ne re que nc y, f L L — the n a r ro w- b a nd le ve l at the to ne re que nc y, f L L NOTE T he va lue s wi th a g re y b ackg ro u nd rep re s e nt the fre quenc ie s a nd n a r ro w- b a nd le ve l s th at, i n the i terati ve procedure, lie more than dB above the mean A-weighted narrow-band level, T2 f k S L , o f the to ne at the to ne = 7, H z wi th the g re ate s t aud ib i l it y, Δ L (>5 4, 2 d B ) , a nd thu s no t co ntr ib ute to th i s le ve l , L S fre que nc y The Hanning correction shall be used for the calculation of the tone level from the narrow-band levels, , in accordance with 5.3.7 Formula (14)], the critical band levels, G , shall be calculated using Formula (12) given in 5.3.5, and the masking index, v , shall be calculated using Formula (13) given in 5.3.6 In this case, there are spectra with to 10 tones, and thus has a value of to and the values 6, 7, and 10 (see Table E.3) All the parameters of the spectrum and the tones = to are presented in Table E.2 Li To de term i ne L the aud ibi l itie s , Δ L j, k [s e e a j, k j j, k k j = ne ce s s a r y to c a lc u late the aud ibi l itie s Δ L j, k k I n add ition to the de term i nation o f the aud ibi l ity, Δ L , o f a tone, it i s a l s o ne ce s s a r y to eva luate its distinctness 28 © ISO 2016 – All rights reserved © ISO 2016 – All rights reserved T a b l e E — Run index Tone L of the tone frequency Formula (14) A k − FG FG fT 1, k in Hz 118,4 137,3 158,8 314,9 433,4 592,2 629,8 643,3 582,7 137,3 592,2 u d i b Δ i l i t y L1, k in dB 1,92 4,99 4,37 1,78 0,87 4,55 1,01 3,47 0,73 9,18 9,12 NOTE The tone with the run index k Δ P a r a m e t e r s f o Lower limit frequency of the critical band Formula (4) f1 1, k in Hz 80,70 96,90 118,40 266,50 382,20 535,60 570,60 584,10 469,60 96,90 535,60 r c a l c u l a t i o n o f Upper limit frequency of the critical band Formula (5) f2 1, k in Hz 177,60 196,50 215,30 371,40 492,60 656,80 694,40 707,90 703,80 196,50 656,80 t h e a u d i b i l i t i e s A-weighted averaged level Formula (6) L S 1, k in dB 48,91 49,22 50,50 52,85 58,29 59,53 59,71 61,98 54,16 49,22 59,53 Δ Lj,k o f t h e f i r A-weighted tone level Formula (7) and Formula (8) LT 1, k in dB 64,56 67,96 68,63 68,50 73,17 78,31 75,00 79,75 71,07 72,15 81,11 s t s p e c t r u m ( j = 1) A-weighted Uncertainty Masking level of the of the index masking noise Formula individual (13) spectrum Formula (12) L G 1, k in dB 64,66 64,98 66,28 68,84 74,52 76,16 76,44 78,74 73,60 64,98 76,16 = FG ( FG me a n s a nu mb e r o f to ne s i n o ne c r i tic a l b a nd) at 7, H z yie ld s the de c i s i ve aud ib i l it y Δ L1 a v 1, k in dB −2 , 01 −2 , −2 , −2 ,1 −2 , −2 ,4 −2 ,4 −2 ,4 −3 , −2 , of 9,18 dB −2 ,4 U in dB 3,66 2,79 3,51 2,46 3,09 2,82 2,67 3,56 2,27 3,21 3,24 ISO/PAS 20065:2016(E) 29 ISO/PAS 20065:2016(E) Step 3: Determination o f the decisive audibility, Δ Lj, Δ L , of all spectra of each spectrum and the mean audibility, The steps necessary to determine the decisive audibility, Δ L , of each individual spectrum are given in 4.3.8 The mean audibility, Δ L , of the noise in accordance with 5.3.9 [see Formula (20) ] is the energy mean value o f the decisive audibilities, Δ L The tone frequencies, fT , and audibilities, Δ L , of all spectra are presented in Table E.3 and the decisive audibilities, Δ L , are presented in bold j j j, k j, k j Table E.3 — All tonal components in the five measured spectra o f a combustion engine Run index of the spectrum, Run index of the tone, Tone frequencies, T 1 118,4 137,3 158,8 314,9 Audibilities, Δ 1,92 4,99 4,37 1,78 — 9,18 — — Audibilities, Δ FG Run index of the spectrum, Run index of the tone, 156,1 430,7 465,7 963,6 Tone frequencies, T 0,52 6,04 0,60 4,11 Audibilities, Δ — — — — Audibilities, Δ FG Run index of the spectrum, Run index of the tone, Tone frequencies, T 118,4 137,3 158,8 433,4 1,77 2,99 2,71 1,78 Audibilities, Δ Audibilities, Δ FG — 7,46 — — Run index of the spectrum, Run index of the tone, Tone frequencies, T 156,1 433,4 465,7 643,3 0,65 2,67 0,25 0,40 Audibilities, Δ Audibilities, Δ FG — — — — Run index of the spectrum, Run index of the tone, Tone frequencies, T 118,4 137,3 156,1 433,4 1,48 2,95 1,50 0,93 Audibilities, Δ — 7,17 — — Audibilities, Δ FG NOTE The values for the decisive differences are presented in bold j k f j, k L j, k L j, k 433,4 0,87 — 592,2 4,55 9,12 629,8 1,01 — 643,3 3,47 — 1582,7 0,73 — — — — — — — — — — — — — — — — — — — — — j k f j, k L j, k L j, k 512,7 590,8 0,27 3,42 — 3,52 j k f j, k L j, k L j, k 589,5 2,56 — 643,3 1,40 — 963,6 512,7 580,0 0,34 2,44 3,48 — — 4,48 707,9 0,35 — 963,6 580,0 1,61 2,14 — — 640,6 2,63 — 699,8 1,73 — — — — — j k f j, k L j, k L j, k — — — — — — — — — — — — j k f j, k L j, k L j, k 942,1 0,00 — 960,9 1,88 2,32 10 512,7 590,8 0,37 2,52 — 2,82 The mean audibility Δ L = 6,96 dB The individual parameters for calculation o f the decisive audibilities, Δ L , o f the five measured spectra are presented in Table E.4 30 j © ISO 2016 – All rights reserved © ISO 2016 – All rights reserved T a b 3-second spectrum Run index j (FG) (FG) (FG) NO TE l e E — P a r a m e t e r s f o r c a l c u l a t i o n o f t h Decisive Lower limit audibility of frequency of Tone an individual the critical frequency spectrum band Formula (14) Formula (4) fT L f1 in Hz 137,3 430,7 137,3 433,4 137,3 j Δ in dB 9,18 6,04 7,46 2,67 7,17 j in Hz 96,90 379,50 96,90 382,20 96,90 j e d e c i s i v e a u d i b i l i t i e s , Δ Lj , o t h e f i v e m e a s u r e d s p e c t r a o f a c o m b u s t i o n e n g i n e Upper limit A-weighted A-weighted frequency of A-weighted Masking Uncertainty of tone level level of the the critical averaged level Formulae index the individual (7) masking noise Formula band Formula (6) (13) spectrum and (8) Formula (12) Formula (5) f2 LS LT LG av U in Hz 196,50 489,90 196,50 492,60 196,50 j in dB 49,22 55,06 50,40 55,12 50,70 j T he s p e c tr u m wi th a g re y b ackg ro u nd (r u n i nde x j = 1) h a s the g re ate s t de c i s i ve aud ib i l i ty, Δ L j of tones in one critical band) f in dB 72,15 75,11 71,61 71,79 71,61 j in dB 64,98 71,29 66,16 71,35 66,46 j in dB j −2 , −2 , −2 , −2 , −2 , 02 in dB 3,21 2,95 2,44 2,52 2,14 , of 9,18 dB; the spectrum is presented in Figure E.1 (FG represents a number ISO/PAS 20065:2016(E) 31 ISO/PAS 20065:2016(E) Clause S t e p : D e t e r I f at le as t m i n a t i o n o f t h e e x t e n d e d u n c e r t a i n t y o f t h e m e a n a u d i b i l i t y , Δ L , in accordance with s p e c tra are eva luate d , then a che ck o f the u ncer tai nty o f the me an aud ibi l ity, Δ L no t ne ce s s a r y (s e e 5.1 , is ) Si nce there are on ly s p e c tra i n th i s c a s e, it i s ne ce s s ar y to che ck that the uncer ta i nty ma rgi n e s no t e xce e d a va lue o f U = ±1,4 dB T he va lue o f the u ncer tai nty ma rgi n i s c a lc u late d as given i n Clause and has a value = ±1,38 dB Since U U i s le s s th an the ma xi mu m s p e c i fie d va lue o f ±1 , d B , the nu mb er o f me a s ure d s p e c tra i s s u fficient (i n view o f the un i form ity o f the noi s e) Step 5: Documentation of the acoustic data In accordance with 7.4, the following acoustic data are to be documented: — line spacing and investigation range (Step 1); — tone frequencies, T , for all spectra (see Table E.3); (Step 3); f j, k, and corre s p ond i ng aud ibi l itie s , Δ L j, k — me an aud ibi l ity, Δ L j — e xtende d u ncer tai nty (Step 4) ; — diagrammatic representation of the narrow-band level of the averaged spectrum with the dominant tone Clause on the measurement procedure, the acoustic surroundings f and on the measurement, recording and evaluation instruments are not given in this example T he o ther i n ormation s p e ci fie d i n 32 © ISO 2016 – All rights reserved ISO/PAS 20065:2016(E) Bibliography [1] ECMA-74:2003-12, Measurement of airborne noise emitted by information technology and telecommunications equipment [2] ANSI S1.13, 1) Measurement of sound pressure levels in air [3] Z wicker [4] [5] [6] [7] [8] 1) E., & Fastl H Psychoacoustics — Facts and Models Springer, 1999 Z wicker E., F lottorp G., S te vens S.S Critical Band Width in Loudness Summation J Acoust Soc Am 1957, 29 pp 548–557 R andall R.B Frequency analysis Brüel & Kjaer, 1987 P lomb R The ear as a frequency analyzer J Acoust Soc Am 1964, 36 pp 1628–1636 P ompe tzki W Vergleich der Tonhaltigkeit nach DIN 45681 mit subjektiven Bewertungen, Fortschritte der Akustik — DAGA ’98 Deutsche Gesellschaft für Akustik e.V., Oldenburg, S 224 — 225 Wiesm ann N., & Fastl H Ausgeprägtheit der Tonhöhe und Frequenzunterschiedsschwellen von Bandpass-Rauschen, Fortschritte der Akustik — DAGA ’91 Deutsche Gesellschaft für Akustik e.V., Oldenburg, S 505508 Reaffirmation o f ANSI S1.13-1995 © ISO 2016 – All rights reserved 33 ISO/PAS 20065:2016(E) ICS 17.140.01 Price based on 33 pages © ISO 2016 – All rights reserved