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1、INTERNATIONAL STANDARD IS0 389-2 First edition 1994-07-l 5 Acoustics - Reference zero for the calibration of audiometric equipment - Part 2: Reference equivalent threshold sound pressure levels for pure tones and insert earphones Acous tique - ZEC 126:1973, /EC reference coupler for the measurement
2、of hearing aids using earphones coup- led to the ear by means of ear inserts. IEC 711:1981, Occluded-ear simulator for the measurement of earphones coupled 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
3、- lowing definitions apply. 3.1 ear insert: Device used to provide the acoustic coupling between an earphone and the ear canal. NOTE 2 This may be, for example, an earmould or a similar device with or without a connecting tube. 3.2 insert earphone: Small earphone coupled to the ear canal by means of
4、 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 simulator: Device for measuring the output sound pressure of an earphone under well-defined loading conditions in a specified frequency range. It c
5、onsists essentially of a principal cavity, acoustic load networks and a calibrated microphone. The location of the microphone is chosen so that the sound pressure at the microphone corresponds approxi- mately to the sound pressure existing at the human eardrum. 1) To be reissued as IS0 388-l. 1 Copy
6、right International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 389-2:1994(E) 0 IS0 3.4 occluded-ear simulator:
7、 Ear simulator which simulates the inner part of the ear canal, from the tip of an ear insert to the eardrum. NOTE 3 An occluded-ear simulator is specified in IEC 711. 3.5 ear-insert simulator (earmould substitute, earmould simulator): Insert which terminates the en- trance of the ear simulator and
8、provides for passage of sound into the acoustic coupler or 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
9、 measure the sound press- ure within the cavity. NOTE 4 An 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 earphon
10、es of type EARTONE 3A are in all relevant aspects identical to ER-3A 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
11、 with a nominal internal diameter of 1,9 mm and a nominal effective 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 so
12、und tube with a nominal internal diameter of 2 mm and a nominal 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 th
13、e entrance of the ear canal. 5 Specifications The reference 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 711, are given in table 1. These values apply when t
14、he sound tube nipple of the insert earphone is fixed flush to the acoustic coupler and to the occluded-ear 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 earph
15、one output and the ear insert simulator is then determined to be 251 mm (see figure2). 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 369:1991 should be used to determine corresponding RETSPL values. Copyrig
16、ht International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 389-2:1994(E) Dimensions in millimetres Sound tube
17、 ER-3A insert earphone 0 1.9 - Sound tube nipple Foam eartip ER-3-16 ear insert Figure 1 - An ER-3-14 ear insert and its coupling to an ER3A insert earphone 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/997254500
18、1 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 389-2:1994(E) 0 IS0 Dimensions in millimetres Figure 2 - Coupling of the insert earphone to the acoustic coupler or to the occluded-ear simulator ER-3A insert earphone , Sound tube a)
19、Acoustic coupler Occluded-ear slmulator - b) Occluded-ear simulator Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without li
20、cense from IHS -,-,- Q IS0 IS0 389-2:1994(E) Table 1 - Reference equivalent threshold sound pressure levels in an acoustic coupler conforming to IEC 126 and in an occluded-ear simulator conforming to IEC 711 Frrquency Hz 125 26.0 1602) 22,0 2002) 18,0 250 14,0 315 12,0 4002) 30 500 5,5 630 4,o 750 2
21、80 80021 185 1 000 a0 1 250 zo 1 500 2.0 1 6002 200 2 000 3.0 2500 5,O 3000 3,5 3 1502) 4.0 4 000 55 5000 5,O 6 000 2.0 6 300 zo 8 000 a0 1) Values are rounded to nearest halfdecibel. RETSPL (ref. 20 pPa1 l) dB Acoustic coupler (IEC 1261 Occluded-ear simulator (IEC 71 I) 28,0 24,5 21.5 17,5 15,5 13.
22、0 9.5 7#5 60 5,5 55 83 9.5 9.5 11,5 13.5 13.0 13.0 15,0 18,5 16,0 16,0 15,5 2) Values for these frequencies are derived by interpolation. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 0
23、4/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 389-2:1994(E) Q IS0 Annex A (informative) Notes on the derivation of RETSPL values The RETSPL values specified in this part of IS0 389 were obtained from the results of three independent exper- imental i
24、nvestigations communicated to lSO/TC 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 the development of this part of IS0 389 were not c
25、orrected for devi- ations of the test subject s hearing threshold levels from 0 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 subjects. Table A.1 - Investigations of RETSPL values
26、 Test data Type of test earphone Measurement method Type of reference earphone Investigations Ref. l Ref. 2 Ref. 3 ERSA insert earphone conforming to clause 4 Hearing threshold technique Reference earphone used to verify normal hearing of test subjects Telephonics Telephonics Beyer TDH-39 TDH-39 DT
27、48 Number of ears tested 56 36 48 Number of subjects 28 18 23 Frequencies tested, in hertz 250, 500, 1 000, 2 000, 125,250, 500, 1 000, 2 000, 125,250, 315, 500,630, 3 000,4 000,8 000 3 000,4 000, 6 000,8 000 750, 1 000, 1 250, 1 500, 2 000, 2 500,3 000,4 000, 5 000,6 000,6 300, 8 000 Hearing thresh
28、old levels of test subjects Type of coupler used for insert earphone 10 dB at any test frequency below 4 000 Hz and 15 dB at test frequencies of 4 000 Hz and above IEC 126:1973, figure 2 IEC 126:1973, figure 2 IEC 126:1973, figure 2 IEC 711:1981, figure 2 IEC 711:1981, figure 2 Copyright Internation
29、al Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,- Q IS0 Annex B (informative) IS0 389-2:1994(E) Bibliography l WILBER,
30、 L.A., KRUGER, B. and KILLION, M.C. Ref- 4 IS0 3894:-3 , Acoustics - Reference zero for erence thresholds for the ER3A insert the calibration of audiometric equipment - earphone. J. Acoust. Sot. Amer., 83 (21, 1988, Part 4: Reference levels for narrow-band mask- pp. 669-676.2 . ing noise. 2 ARLINGER
31、, S. and KINNEFORS, C. Reference equivalent threshold sound pressure levels for insert earphones. Stand. Audio/., 18, 1989, pp. 195-l 98. 5 IEC 303: 1970, /EC provisional reference coupler for the calibration of earphones used in audiometry. S BRINKMANN, K. and RICHTER, U. Reference zero for the cal
32、ibration of pure tone audiometers equipped with insert earphones. Acusrica, 70, 1990, pp. 202-207. 6 IEC 318:1970, An /EC artificial ear, of the wide- band type, for the calibration of earphones used in audiometry. 2) This article is a compilation of the results of five experimental studies. For the
33、 purposes of this part of IS0 389, however, the results of one study only (Wilber, 1986) could be taken into account due to deviating test conditions used in the other studies. 3) To be published. Copyright International Organization for Standardization Provided by IHS under license with ISO License
34、e=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 389-2:1994(E) 0 IS0 ICS 13.140.00 Descriptors: acoustics, audiometry, audiometers, calibration, auditory threshold, reference data. Price based on 7 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/23/2007 21:29:05 MDTNo reproduction or networking permitted without license from IHS -,-,-