1、CEN EN*248bq-L 92 W 3404589 0054094 09b EUROPEAN flmm NO= EUROPENNE EUROPALSCHE NORM EN 24869-1 October 1W2 UDC 614.892 620.1 : 534.61 : 534.833.5 Descriptors: Acoustics, ear protectors, acoustic measurement, noise reduction English version Acoustics - Hearing protectors - Subjective method for the
2、measurement of sound attenuation (IS0 48691 : 1990) Acoustique - Proteckurs individuels contre le bruit - Mthode subjective de mesurage de laffaiblissement acoustique Akustik - Gehrschtzer - Subjektive Methode zur Messung der Schalldammung (EO 4869-1 : 1990) USO 4869-1 : 1990) This European Standard
3、 was approved by CEN on 1992-10-16. CE3 members are bound to comply with the CENKENELEC Internal Regulations which stipuiate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nati
4、onai standards may be obtained on appiication to the Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, Gem). A version in any other language made by translation under the responsibility of a CEN member into its own language and notin
5、ed to the Central Secretariat has the same status as the officiai versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
6、 CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fur Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1992 Copyright reserved to CEN members Ref. No. EN 24869-1 : 1992 E CEN EN*248b9-L 92 W 3404589 O054095 T22 W Page 2 EN 24869-1 : 1992
7、 Foreword This European Standard is the endorsement of Is0 48691. Endorsement of Is0 4869-1 was recommended by Technical Committee CENRC 211 Acoustics under whose competence this European Standard will henceforth fali. This European Standard shall be given the stahis of a national standard, either b
8、y publication of an identical text or by endorsement, at the latest by April 1993, and conflicting nationai standards shall be withdrawn at the latest by April 1993. The Standard was approved and in accordance with the CEN/CENELEC Internal Regulations the following countries are bound to implement t
9、his European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, Unite Kingdom. CEN EN*248b9-l1 92 m 3404589 O054096 9b9 m INTERNATIONAL STANDARD IS0 4869-1:l-990(E) Acoustics - Hearing
10、 protectors - Part 1: Subjective method for the measurement of sound attenuation 1 Scope This International Standard specifies a subjective method for measuring sound attenuation of hearing protectors at the threshold of hearing. The method and procedures are designed to yield values close to the ma
11、ximum attenuation which are not normally attained under field conditions. This approach has been adopted because the attenuation values can then be consistently reproduced. The values reflect the attenuating characteristics of the hearing pro- tector only to the extent that users wear the device in
12、the same manner as did the test subjects. This test method yields data which are collected at low sound pressure levels (close to the threshold of hearing) but which are also representative of the attenuation values of hearing protectors at higher sound pressure levels. An exception occurs in the ca
13、se of amplitude-sensitive hearing protectors for sound pressure levels above the point at which their level-dependent characteristics become effective. At those sound pressure levels the method specified in this International Standard is inapplicable; it will usually underestimate sound attenuation
14、for these devices. NOTE 1 At low frequencies (below 500 Hz) the sound attenuation may be overestimated by a few decibels as a result of masking the occluded ear thresholds caused by physiological noise during the occluded ear tests. 2 Normative references The following standards contain provisions w
15、hich, through reference in this text, constitute provisions of this pari of IS0 4869. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this pari of IS0 4869 are encouraged to investi- gate the possibility of appl
16、ying the most recent edi- tions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International Standards. IS0 354:1985, Acoustics - Measurement of sound absorption in a reverberation room. IS0 8253-2:-ll, Acoustics - Audiometric test meth- ods - Part 2:
17、Sound field audiometry with pure fone and narrow-band test signals. IEC 225: 1966, Octave, half-octave and third-octave band filters intended for fhe analysis of sounds and vibrations. IEC 263:1982, Scales and sizes for plotting frequency characteristics and polar diagrams. IEC 645-1:-,*) Audiometer
18、s - Part 1: Pure tone audiometers. IEC 651:1979, Sound levei meters. - 4 - IEC 804: 1985, lntegrating-averaging sound level meters. 3 Definitions For the purposes of this part of IS0 4869, the follow- ing definitions apply. 3.1 hearing protector: A device worn by a person to prevent unwanted auditor
19、y effects from acoustic stimuli. 1) To be published. 2) To be published. (Revision of IEC 6451979.) 1 CEN EN*Z4869-1 92 m 3404589 0054097 8T5 m IS0 4869-1 11 990( E) NOTE 2 Hearing protectors may include electronic de- vices for communication or devices designed to play an active role in the reducti
20、on of the noise level between the hearing protector and the ear-drum. 3.2 ear-muff: A hearing protector consisting of an ear-cup to be pressed against each pinna or of a circumaural ear-cup to be pressed against the head around the pinna. The ear-cups can be pressed against the head with a special h
21、eadband or neck- band or by means of a device attached to a safety helmet or other equipment. 3.3 ear-plug: A hearing protector worn within the external ear canal (aural) or in the concha against the entrance to the external ear canal (semi-aural). 3.4 helmet: A device which covers a substantial par
22、t of the head. 3.5 hearing level (of a pure tone): At a specified frequency, for a specified type of earphone and for a specified manner of application, the sound pres- sure level of this pure tone produced by the earphone in a specified acoustic coupler or artificial ear minus the appropriate refer
23、ence equivalent threshold sound pressure level. NOTE 3 pressure leveis are Specified in IS0 389. Values of reference equivalent threshold sound 3.6 hearing threshold level (of a given ear): At a specified frequency and for a specified type of earphone, the threshold of hearing expressed as hearing l
24、evel. NOTE 4 ple, IS0 6189 and IS0 8253-1. For appropriate test conditions see. for exam- 3.7 threshold of hearing: The lowest sound pres- sure level at which, under specified conditions, a person gives a predetermined percentage of correct detection responses on repeated trials. NOTE 5 For the purp
25、ose of this International Standard, the threshold of hearing is measured with and without the hearing protector. For appropriate test conditions, see IS0 8253-2. 3.8 sound attenuation: For a given test signal, the difference, in decibels, between the threshold of hearing with and without the hearing
26、 protector in place for a test subject. 3.9 pink noise: Noise the sound pressure spectral density of which is inversely proportional to fre- q u en cy. 3.10 reference point: The midpoint of a line con- necting the test subjects ear canal openings. 3.11 reverberation time: The time required for the s
27、ound pressure level to decrease by 60 dB after the sound source has stopped (see IS0 354). 3.12 repeatability: The value below which the ab- solute difference between two single test results obtained with the same method on identical test material, under the same conditions (same operator, same appa
28、ratus, same laboratory, and a short in- terval of time), may be expected to lie with a speci- fied probability; in the absence of other indications, the probability is 95 Oh. 3.13 reproducibility: The value below which the absolute difference between two single test results obtained with the same me
29、thod on identical test material, under different conditions (different opera- tors, different apparatus, different laboratories and/or different time), may be expected to lie with a specified probability; in the absence of other indi- cations, the probability is 95 Oh. 4 Measurement of the sound att
30、enuation of hearing protectors 4.1 Test signals The test signals shall consist of a signal from pink noise filtered through one-third octave bands with centre frequencies in accordance with IEC 225. Tests shall be performed at the following centre frequen- cies: 63 Hz (optional) 125 Hz 250 Hz 500 Hz
31、 loo0 Hz 2000 Hz 4000 Hz 8000 Hz 4.2 Test site 4.2.1 Diffuse sound field conditions are required and are adequately approximated when the follow- ing requirements are met: a) With the test subject and the subjects chair ab- sent, the sound pressure level measured with an omnidirectional microphone a
32、t positions 15 cm from the reference point on the front-back, right- lef and up-down axes shall deviate by no more than f 2.5 dB from the sound pressure levei at 2 CEN EN*24869-L 92 m 3404589 0054098 731 W the reference point for any of the test signals. Further, the difference between the extreme r
33、ight-left positions shall not exceed 3 dB. The orientation of the microphone shall be kept the same at each position. b) At frequencies of 500 Hz and above, the sound pressure level at the reference point shall be within 5 dB for the two directions of measure- ment that give maximum and minimum read
34、ings of the incident sound energy when measured with a directional microphone with a front-to- random sensitivity index of 5 dB. For other di- rectional microphones the relationship between front-to-random sensitivity index and the allow- able field variation is given in table 1. Table 1 - Allowable
35、 field variation for different microphones I Front-to-random sensitivity index I Allowable eld variation 4 Microphone not suitable I NOTES 1 The test should be carried out in a sufficient number of directions. which depend on the type of microphone and the characteristics of the loudspeaker arrangem
36、ent and include at ieast the two planes where maximum and minimum sound pressure levels may be expected. 2 More than one loudspeaker is necessary to produce the desired sound field. The loudspeakers may require to be fed with non-coherent electrical signais to reduce the effects of standing waves. 4
37、.2.2 The reverberation time in the test space (without subject) shall not exceed 1.6 s for each of the test bands. 4.2.3 The background noise at the test site in the test room shall not exceed the values given in table 2 with the test subject absent. The background noise shall be determined by measu
38、ring the sound pressure level. IS0 4869-1 :i 990(E) - Table 2 - Maximum permissible background sound One-third octave band sound Centre frequency Hz 31,5 1 40 ) 50 +) 63 80 1 O0 125 1 60 200 250 315 400 500 630 E00 IO00 1 250 1600 2 o00 2500 3 150 4000 5 O00 6 3 SOO0 1om pressure level (reference =
39、20 pPa) 57 43 31 25 21 10 14 11 9 6 4 3 2 1 1 1 1 2 2 1 -1 -4 -2 3 10 20 ) For a minimum test band centre frequency of 125 Hz, the background noise requirement shall be met down to and In- cluding 63 Hz. For a minimum test band centre frequency of 63 Hz, the background noise requirement shall be met
40、 down to and including 31,5 Hz. 1 4.3 lest equipment 4.3.1 The test equipment shall be capable of prod- ucing a test signal at the test site from 112 Hz the lower iimiiing frequency of the 125 Hz one-third octave band (or 56 Hz if the 63 Hz test band centre frequency is to be used) to 9 Hz the upper
41、 limiting frequency of the 8000 Hz one-third octave band. The equipment, including the loudspeaker system, shall be able to produce the minimum and maximum test signal sound pressure levels given in table3 at the test subjects position. NOTE 6 Background noise includes the ambient noise present in t
42、he room and the noise of the test equipment in the absence of the test signal. 3 CEN EN*:248b9-L 92 3404589 0054099 b78 Centre frequency HZ 63 ) 125 250 500 1 OM) 2 2000 IS0 4869-1 1-1 990(E) Minimum and maximum lest signal sound pressure levels (reference = 20 fiPa) d0 10 to 80 *) -5 to 70 -10 to 7
43、0 -15 to ao -20 to ao -20 to 90 I I I -iate I *) Distortion limits given in the text shall be met up to at least a 70 dB sound pressure level. I The distortion factor of the equipment, including the loudspeaker system, shall secure the reproduction of the test signals without any audible crackle and
44、 rattle at each test band and each level as given in table 3. At centre frequencies from one octave above the test band up to 16 kHz and from one octave be- low the test band down to 31,5 Hz, all one-third octave band sound pressure levels shall remain at least 40 dB below the sound pressure level i
45、n the test band all the time under all test conditions. The band levels shall be measured using filters comply- ing with IEC 225. The test band sound pressure lev- els shall be measured as average values (IJeq in IEC 804) and the remaining band levels using time weighting F of IEC 651. 4.3.2 Attenua
46、tor steps shall be 2,5 dE? or smaller. 4.3.3 The error in the difference between the indi- cations at any two positions of the attenuator with the complete test equipment including the loud- speaker shall not exceed 2 dB over the total range of the attenuator and I dB over any 80 dE3 range. Where po
47、ssible, this test shall be performed acous- tically. At low sound pressure levels it is also per- missible to check the test equipment by electrical measurement of the signal voltage at the terminals of the loudspeaker(s). If it is not possible to achieve the desired accuracy in the attenuation syst
48、em, the test equipment shall be calibrated and the corrections thus obtained shall be applied to the measurements. 4.3.4 The electrical signals applied to the loud- speakers shall comply with IEC 645-1. 4.4 Test subjects 4.4.1 Subjects to be used in the tests shall have a hearing threshold level by
49、earphone listening in either ear of no more than 15 dB for frequencies of 2000 Hz and below, and of no more than 25 dB for frequencies above 2000 Hz. When the background noise in the test room is at the maximum levels listed in table2, subjects with hearing threshold levels lower than -10 dB shall be rejected. 4.4.2 Subjects shall be selected without regard to sizes and shapes of heads and ears except that those with obvious abnormalities affecting the fitting of hearing protectors shall be excluded. 4.4.3 Subjects used for the test shall have demon- stra
