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1、4851703 Ob03883 Tb4 I NT E R NAT I O NA L STANDARD IS0 7196 First edit ion 1995-03-1 5 Acoustics - Frequency-weighting characteristic for infrasound measurements Acoustique - Pondration frquentielle pour le rnesurage des infrasons Reference number IS0 71 96:1995(E) COPYRIGHT International Organizati
2、on for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services - _ _ 4851903 Ob0188Y ?TO IS0 7 196: 1995(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation
3、 of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 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.
4、International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnicai standardization. Draft International Standards adopted by the technica
5、l committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 YO of the member bodies casting a vote. International Standard IS0 71 96 was prepared by Technical Committee ISOflC 43, Acoustics, Subcommittee SC 1, Noise. Annexes
6、A and B of this International Standard are for information only. O IS0 1995 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm. without permission in wr
7、iting from the publisher. International Organization for Standardization Case Postale 56 CH-1 21 1 Genve 20 Switzerland Printed in Switzerland II COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardizatio
8、n Licensed by Information Handling Services 8 IS0 W 4853703 0603885 837 W IS0 7 196: 1995( E) Introduction Methods have already been standardized for the description and assess- ment of noise from various sources and with respect to various effects on human subjects (risk of hearing damage, annoyanc
9、e reactions, loud- ness, perceived noisiness, interference with speech communication). These methods are described in outline in IS0 2204 and in detail in other International Standards, including IS0 226, IS0 1996-1, IS0 1999, ISO/TR 3352 and IS0 3891. In all these cases, the bandwidth of the noise
10、is either considered to lie within the conventional audio frequency limits from 20 Hz to 20 O00 Hz or within a specified narrower band (for example, 45 Hz to 11 200 Hz in the case of perceived noisiness of aircraft). The band limits of 20 Hz and 20 O00 Hz also define the frequency range for which th
11、e characteristics of sound level meters are fully specified (see IEC 651). In practice, some noises consist of, or contain components at, frequencies below 20 Hz. At present, there are no standardized methods for sound pressure measurements of these noises, nor for their description and as- sessment
12、 with respect to human response. Although research in this field is comparatively sparse, there is evidence of infrasonic effects which are potentially harmful or unpleasant to human subjects and some authorities may desire to extend their regulations or codes of practice governing noise emissions t
13、o cover sources of infrasound. For this reason, it is considered to be highly desirable to standardize measurement and description methods in order to facilitate the exchange of information and to avoid proliferation of incompatible procedures. Many types of human response can be distinguished and,
14、correspond- ingly, different description methods are, in principle, appropriate. The method described in this International Standard corresponds to the direct perception of infrasound. At present, this is the only human response for which there is an ample research base. Some literature on annoyance
15、 from infrasound suggests that annoyance may be closely related to the direct perception. On that precondition, levels measured according to this International Standard would reflect the annoyance as well as the direct perception. The perception of infrasound, although apparently achieved through th
16、e auditory mechanism, differs in some respects from that usually under- stood by hearing. The normal threshold of perception is considerably higher than at audio frequencies (about 100 dB relative to 20 pPa at 10 Hz), whilst toleration for high levels is not raised correspondingly, that is, the dyna
17、mic range is smaller and the rate of growth of sensation with sound pressure level is much more rapid. In the frequency range 1 Hz to 20 Hz, sounds that are just perceptible to an average listener will yield weighted sound pressure levels close to 100 dB when measured in ac- cordance with this Inter
18、nationai Standard. A very loud noise will yield a weighted level in the order of 120 dB, only 20 dB above. Weighted sound pressure levels which fall below about 90 dB will not normally be signifi- cant for human perception. . 111 COPYRIGHT International Organization for Standardization Licensed by I
19、nformation Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services IS0 7 196: 1995(E) W 4851903 ObO1b 773 0 IS0 Attention should be paid to the fact that, due to the combined effect of individual differences in perception threshold and the
20、 steep rise in sen- sation above the threshold, the same infrasonic noise may appear loud and annoying to some people while others can hardly perceive it. Publication of this International Standard is not intended to inhibit research into infrasonics, for which methods of physical measurement other
21、than those specified here may be appropriate, for example frequency analysis. The specification of measuring equipment for use in conjunction with this International Standard is expected to be undertaken by Technical Com- mittee I EC/TC 29. This International Standard contains an informative an- nex
22、 A outlining requirements for instrumentation to measure weighted levels, which may be used until a suitable IEC standard has been issued. It should be emphasized that the measurement and description of a wide-band noise, containing infrasonic components, in accordance with this International Standa
23、rd shall be considered as being independent of, and supplementary to, the measurement, description and assessment of the same noise by the methods defined in existing International Stan- dards. A bibliography is given for information in annex B. iv COPYRIGHT International Organization for Standardiz
24、ation Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services 4853903 0603887 bOT = INTERNATIONAL STANDARD 0 IS0 IS0 7196:1995(E) Acoustics - Frequency-weighting characteristic for infrasound measurements 1 Scope Th
25、is In4emtioml Standard specifies a frequency- weighting chaad-tjc, designated G. for the deter- rniriardion OB weighted sound pressure levels of sound or noise wkme spemurn hex+ port the w e af wideband noises whose spectrum em- braces- both, the infiramnic and audio-frequency ranges, use of, this I
26、nternational. Standard to determine the infrasonic w e i g h t sound pesure level is supplementary to the de- scription of sime noise by methods already standard- ized which cover the audio-frequency range only, for example the descriptkm in terms of A-weighted sound pressure level. The numerical va
27、lue of the results will, in general, differ from the G-weighted result. No significance should be attached to this difference. since the respective results relate to different parts of The noise spectrum with little overlap. 2 The G-weighting can also be used in connection with the determination of
28、sound power levels and sound intensity levels. When measured with the G-curve, these are sym- bolized respectively as kG and L,G. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time
29、of publi- cation, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate: the possibility of applying the most re- cent edition of the standard indicated below. Mem- bs of IEC and IS0 mainta
30、in registers of currently valid International Standards. I EC 651 :I 979, Sound level meters. 3 Definitions For the purposes of this International Standard, the following definitions apply. 3.1 infrasound: Sound or noise whose frequency spectrum lies mainly in the band from 1 Hz to 20 Hz. 3.2 audio-
31、frequency sound: Sound or noise whose frequency spectrum lies mainly in the band from 20 Hz to 20 O00 Hz. 1 COPYRIGHT International Organization for Standardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Ser
32、vices IS0 7196:1995(E) I + j 1 O + j O O + j O O + j O 3.3 wide-band sound: Sound or noise which con- sists partly of infrasound and partly of audio-frequency sound. 3.4 G frequency weighting: Frequency weighting of a signal by means of the frequency-response characteristic as defined in clause 4. 3
33、.5 G-weighted sound pressure level: Sound pressure level given by the formula: where - p2 is the mean-square value of the G-weighted sound pressure; po is the reference sound pressure (20 pPa). Sound pressure levels are expressed in decibels. NOTE 3 When there is no possibility of misunder- standing
34、 (for example with the expressions in clause 1, note 21, LpG may be abbreviated to 5 Reporting of results When measuring the sound pressure level aPPlYing G-weighting using appropriate instrumentation, for C) the characteristics of the detector; example that given in annex A, results shall be ac- co
35、mpanied by the following data: d) the estimated uncertainty of the measured levels; a) the calibration of the measuring system, including frequency response; e) all relevant details of place, time and conditions prevailing during the measurements. 3 COPYRIGHT International Organization for Standardi
36、zation Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services IS0 7 196: 1995(E) Annex A (informative) Outline requirements for equipment for measuring infrasound A.l General The frequency weighting is designed to
37、be introduced into an instrumentation system having an otherwise constant frequency response. Alternatively, part of the frequency weighting can be omitted from the weighting filter and included elsewhere in the instru- mentation system, so that the entire system exhibits the same performance. The s
38、ystem should be de- signed to indicate the level of the root-mean-square sound pressure in decibels relative to 20 UPa. A.2 Microphone input within a specified accuracy and over a specified dynamic range. The characteristics should be stated when reporting the results of noise measurements and shoul
39、d not be less stringent than those specified for sound level meters of type 1 having the F or S time-weighting characteristics (see 9.4.2 of IEC 651:1979). A.5 Integrator-indicator The integrator-indicator should display, in decibels, the mean value of the detector output signal. The integrator may
40、have a rectangular time window or be of the RC-type, having an exponential time window. The integrating time constant chosen should be suffi- ciently long for the observed value to be represent- ative of the noise being measured. Usually. this will The microphone should have a substantially constant
41、 or well-defined frequency response over at least the frequency range from 0,25 Hz to 160 Hz, preferably the range 0,25 Hz to 315 Hz. N(JE 4 There is no practical limit on the dimensions of be the Case for an integration tme/tim? COllStZ3tlt Of the microphone since directional effects will be neglig
42、ible in the inkasonic frequency range. 10 s. When frequencies i n the upper gart of the 1 Hz to 20 Hz band mainly contribute, a value as J w as 1 s may be used. A.3 rlbaynlfier and frequency-weighting circuit The amplifier and frequency-weighting circuit of the instrumentation system should be desig
43、ned to avoid overload and, bari conjunction with the microphone, to produce the overaft frequency-weighting characteristic G. Relative to the gain at IO Hz, the response of the system should conform as as possible Q the characteristic specified in cb 4, b u s o;f the steep rise in sensation with cou
44、r$! pressure Iwefli s- curacy is cmcial and more importan? 1Rm a$ aw$ frequencies. For the frequency range 1 Hz to 20“k, the tolerance range should not exceed f 1 dB, and for frequencies below 1 Hz and above 20 Hz, a toler- ance range of - 00 ta + 1 dB can be applied to the nominal values. A.4 Detec
45、tor The detector should deliver an output which is pro- portional to the square of the electrical signal at its For fluctuating noise, a rectangular time window of at least 1 min is recommended. In this case the re- ported value is denoted equivalent G-weighted sound pressure level, LpGreq. The i n
46、b m r m y be of the analog, d?ontinuiow analog (serimm6 brnps) or digital type, a s sperMedfw sound level metew A digital: indica The owe all inrnrnentation system, from microphone to indicata dsplaiy, should be calibrated for sinusoidal inputs over at; least the frequency range from 0,5 Hz to 160 H
47、z, and preferably the range from 0,25 Hz to 315 Hz, at the frequencies given in table2. The gain of the system should be adjusted so that, for an input signal at 10 Hz, the indicator reads the true sound pressure level, in decibels relative to 20 pPa. 4 COPYRIGHT International Organization for Stand
48、ardization Licensed by Information Handling Services COPYRIGHT International Organization for Standardization Licensed by Information Handling Services W 4851903 Ob0189L 030 W 0 IS0 IS0 7196:1995(E) The calibration should be carried out at a level within the linearity range of the instrumentation sy
49、stem and comparable with that of the noises which the appar- atus is intended to measure. A.7 Method for approximate ,.Jetermination of -ihd sound pressure level An approximate determination of the G-weighted sound pressure level may be made by band analysis of the signal using bandwidths no greater than one- third octave and application of the weighting values The calibration may be partly acousto-electrical and partly electrical, provided that no loss of accuracy en- sues. given in table2. 5 COPYRIGHT International Organization for Standardization
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