EN ISO 389-2-1996 en Acoustics - Reference Zero for the Calibration of Audiometric Equipment - Part 2 Reference Equivalent Threshold Sound Pressure Levels for Pure Tones and Insert.pdf
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1、STD-BEI BS EN IS0 387-2-ENGL 1777 1bZqbb7 0577705 810 M BRITISH STANDARD Acoustics - Reference zero for the calibration of audiometric equipment Part 2. Reference equivalent threshold sound pressure levels for pure tones and insert earphones The European Standard EN IS0 3892 : 1996 has the status of
2、 a British Standard ICs 13.140; 17.140.50 NO COPYING WITHOUT BSI PEFWISSION EXCEPT AS PEtC 126:1973, IEC reference coupler for the measurement of hearing aids using earphones coup- led to the ear by means of ear inserts. IEC 71 1 :1981, Occluded-ear simulator for the measurement of earphones coupled
3、 to the ear by ear inserts. 3 Definitions For the purposes of this part of IS0 389, the defi- nitions given in IS0 389:1991 together with the fol- lowing definitions apply. 3.1 ear insert: Device used to provide the acoustic coupling between an earphone and the ear canal. NOTE 2 similar device with
4、or without a connecting tube. This may be, for example, an earmould or a 3.2 insert earphone: Small earphone coupled to the ear canal by means of an ear insert, or attached to a connecting element which is inserted into the ear ca- nal. The ear insert may be a part of the insert earphone. 3.3 ear si
5、mulator: Device for measuring the output sound pressure of an earphone under well-defined loading conditions in a specified frequency range. it consists essentially of a principal cavity, acoustic load networks and a calibrated microphone. The location of the microphone is chosen so that the sound p
6、ressure at the microphone corresponds approxi- mately to the sound pressure existing at the human eardrum. 1) To be re-issued as IS0 389-1. STD-BSI BS EN IS0 389-2-ENGL 1997 m 3b24bb9 0597933 997 IS0 389-2:1994(E) 3.4 occluded-ear simulator: Ear simulator which simulates the inner part of the ear ca
7、nal, from the tip of an ear insert to the eardrum. NOTE 3 An occluded-ear simulator is specified in IEC 71 1. 3.5 ear-insert simulator (earmould substitute, earmould simulator): Insert which terminates the en- trance of the ear simulator and provides for passage of sound into the acoustic coupler or
8、 the occluded-ear simulator through an opening on its axis. 3.6 acoustic coupler for insert earphones: Cavity of specified shape and volume which is used for the calibration of an insert earphone in conjunction with a calibrated microphone to measure the sound press- ure within the cavity. NOTE 4 An
9、 acoustic coupler for insert earphones is specified in IEC 126. 4 Type of earphone This part of IS0 389 applies to insert earphones of type Etymotic Research ER3A, coupled to the human ear by ear inserts of type ER-3-14. NOTE 5 insert earphones of type EARTONE 3A are in all relevant aspects identica
10、l to ER3A insert earphones. Ear inserts of type ER-3-14 are also offered as EARLINK 3A ear inserts. The ear insert consists of a foam eartip with a nominal diameter of 13 mm and a nominal length of 12 mm. It contains an internal plastic tube with a nominal internal diameter of 1.9 mm and a nominal e
11、ffective length of 22 mm, as measured between the end of the foam eartip and the end of a sound tube nipple (nominal internal diameter 1,9 mm, nominal length 11 mm). The nipple connects the ear insert to the in- sert earphone output via a sound tube with a nominal internal diameter of 2 mm and a nom
12、inal effective length of 240 mm, as measured between the end of the nipple and the end of the earphone output (see figure 1). The ear insert shall be inserted into the ear canal so that the outer end of the eartip is 2 mm to 3 mm in- side the entrance of the ear canal. 5 Specifications The reference
13、 equivalent threshold sound pressure levels (RETSPL) for earphones as specified in clause 4, in an acoustic coupler conforming to IEC 126 and in an occluded-ear simulator conforming to IEC 71 1, are given in table 1. These values apply when the sound tube nipple of the insert earphone is fixed flush
14、 to the acoustic coupler and to the occludedear simulator in accordance with figure 2 of IEC 126:1973 or IEC 711:1981, respect- ively, by means of plastic tubing. The total effective length of the connecting elements between the insert earphone output and the ear insert simulator is then determined
15、to be 251 mm (see figurez). NOTE 6 In the case of audiometers fitted with insert earphones other than that described in clause 4, the pro- cedure given in A.2.2 of IS0 389:1991 should be used to determine corresponding RETSPL values. 2 IS0 389-2:1994(E) Dimensions in millimetres I Sound tube - / - S
16、ound tube nipple I w 0 13 Figure 1 - An ER-3-14 ear insert and its coupling to an ER-3A insert earphone 3 STD*BSI BS EN IS0 387-2-ENGL 3777 H lbZqbb9 0597735 7bT IS0 389-2:1994(E) Dimensions in millimetres Figure ER-3A insert earphone Sound tube HH Sound tube nipple Tube-coupling device Ear-insert s
17、imulator Occluded-ear simulator a) Acoustic coupler b) Occluded-ear simulator 2 - Coupling of the insert earphone to the acoustic coupler or to the occluded-ear simulator 4 Table 1 - Reference equivalent threshold sound pressure levels in an acoustic coupler conforming to IEC 126 and in an occluded-
18、ear simulator conforming to IEC 711 Frequency Hz 125 1602) 2002) 250 31 5 4002) 500 630 750 8002) 1 O00 1 250 1 500 1 6002, 2 O00 2 500 3 000 3 1502) 4 O00 5 O00 6 O00 6 300 a o00 RET= (ref. 20 pPa) 1) dB Acoustic coupler (IEC 126) 26,O 22,o 18,O 14,O 12.0 9,o 5.5 2,o 13 0,0 2.0 2.0 2,o 3.0 5,O 3.5
19、4.0 5,5 5,O 2.0 2.0 0,o 4,0 Occluded-ear simulator (IEC 71 i) 28.0 24,s 21.5 17,5 153 13,O 9.5 7,5 6.0 5,5 5.5 8,s 9.5 9.5 11,5 13.5 13.0 13.0 15.0 18.5 16.0 16.0 15,5 1) Values are rounded to nearest halfdecibel. 21 Values for these frequencies are derived by interpolation. 5 - STD-BSI BS EN IS0 38
20、7-2-ENGL 1777 3b2YbbS 0577937 532 IEC 126:1973, figure 2 IS0 389-21 994( E) IEC 126:1973, figure 2 IEC 711:1981, figure 2 IEC 126:1973, figure 2 IEC 711:1981, figure 2 Annex A (informative) Notes on the derivation of RETSPL values The RETSPL values specified in this part of IS0 389 were obtained fro
21、m the results of three independent exper- imental investigations communicated to iSO/lC 43, Acoustics. Brief particulars of the tests are given in tableA.l. More details on measurement methods and test subjects are given in the references quoted in annex B. The insert earphone threshold data used in
22、 the development of this part of IS0 389 were not corrected for devi- ations of the test subjects hearing threshold levels from O dB, as measured with the reference earphone. The RETSPL data were derived by averaging the data of the three investigations without weighting for different numbers of sub
23、jects. Table A.l - Investigations of RETSPL values Test data Type of test earphone Measurement method Type of reference earphone Number of ears tested Number of subjects Frequencies tested, in hertz Hearing threshold levels of test subjects Type of coupler used for insert earphone investigations Ref
24、. l I Ref. 2 I Ref. p _ ER3A insert earphone conforming to clause 4 Hearing threshold technique Reference earphone used to verify normal hearing of test subjects Telephonics TDH-39 56 28 250, 500, 1 000, 2 000, 3 000,4 000,8 O00 Telephonics TDH-39 36 18 125,250, 500, 1 000, 2 000, 3 000,4 000,6 000.
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