AS/NZS 1591.1:1995

1 - AS/NZS 1591.1:1995 ACOUSTICS - INSTRUMENTATION FOR AUDIOMETRY - REFERENCE ZERO FOR THE CALIBRATION OF PURE-TONE BONE CONDUCT
4 - PREFACE
5 - CONTENTS
6 - INTRODUCTION
9 - 1 Scope
9 - 2 Normative references
10 - 3 Definitions
10 - 3.1 bone conduction:
10 - 3.2 bone vibrator:
10 - 3.3 alternating force level (force level)
10 - 3.4 mechanical coupler:
10 - 3.5 equivalent threshold force level
10 - 3.6 reference equivalent threshold force level (RETFL)
10 - 3.7 hearing level
10 - 3.8 occlusion effect:
10 - 3.9 masking:
10 - 3.10 datum level of masking noise:
10 - 3.11 critical bandwidth:
10 - 3.12 vibrotactile threshold level:
10 - 3.13 white noise:
11 - 4 Reference equivalent threshold force levels (RETFLs)
11 - 5 Test conditions and requirements
11 - 5.1 Bone vibrator
11 - 5.2 Fitting of the bone vibrator
11 - 5.3 Mechanical coupler
11 - 5.4 Test signal
12 - 5.5 Masking noise
12 - 5.6 Masking transducer
12 - 5.7 Fitting of masking transducer
12 - 5.8 Datum level of masking noise
13 - Annex A - Note on the derivation of RETFL values
14 - Annex B - Guidance on the application of the reference zero to the calibration of bone-conduction audiometers
14 - B.1 General
14 - B.2 Choice and fitting of bone vibrator
14 - B.3 Calibration of the bone vibrator
14 - B.4 Choice and fitting of masking transducer
14 - B.5 Masking noise source
15 - Annex C - Interim differences in reference equivalent threshold force levels between forehead and mastoid location of vibrato
17 - Annex D - Bone-conduction threshold of hearing for frequencies below 250 Hz
18 - Annex E - Bibliography

Specifies reference equivalent threshold force levels, essential characteristics of the bone vibrator and levels of masking noise applied to the ear not under test. These are applicable to the calibration of bone vibrators for pure-tone bone conduction audiometry. It is identical with and has been reproduced from ISO 389-3:1994.

This part of ISO 389 specifies the following data applicable to the calibration of bone vibrators for pure-tone bone-conduction audiometry.a) Reference equivalent threshold force levels (RETFLs), corresponding to the threshold of hearing of young otologically normal persons by bone-conduction audiometry. RETFL is the vibratory force level transmitted to a mechanical coupler of specified characteristics (see 5.3) by a vibrator when applied to the mechanical coupler under stated conditions of test and when energized at the voltage level corresponding to the normal threshold of hearing for location on the mastoid prominence.NOTE 1 Interim values for the differences in reference equivalent threshold force levels between location on the forehead and mastoid are included for information in annex C.b) Essential characteristics of the bone vibrator and of its method of coupling to a person under test and to the mechanical coupler.c) Essential characteristics and datum level of the masking noise applied to the ear not under test.Guidance on the practical application of this part of ISO 389 in the calibration of audiometers is given in annex B.NOTE 2 Recommended procedures for carrying out bone-conduction audiometry are specified in ISO 8253-1.

First published as Joint Standard AS/NZS 1591.1:1995.