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AS/NZS 1935.1:1998


Acoustics — Determination of sound absorption coefficient and impedance in impedance tubes, Part 1: Method using standing wave ratio

Specifies a method for the determination of the sound absorption coefficient, reflection factor and surface impedance or surface admittance of materials and objects. This Standard is technically equivalent to and has been reproduced from ISO 10534-1:1996.
Published: 05/05/1998
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Table of contents
Cited references
Content history
Table of contents
About this publication
1 Scope
2 Normative references
3 Definitions
4 Principle
5 Fundamentals
5.1 General conditions
5.2 Formulae
5.3 Inter-relationships
5.4 Standing wave
5.5 Sound absorption coefficient
5.6 Reflection factor
5.7 Impedance
5.8 Wavelength
6 Test equipment
6.1 Impedance tube
6.1.1 Construction
6.1.2 Working frequency range
6.2 Test-sample holder
6.3 Microphone
6.3.1 Microphone with probe tube
6.3.2 Microphone in the impedance tube
6.3.3 Acoustic centre of the probe microphone
6.4 Device for moving and positioning the microphone
6.5 Signal-processing equipment
6.6 Loudspeaker
6.7 Signal generator
6.8 Loudspeaker termination
6.9 Thermometer
7 Preliminary tests and measurements
8 Mounting of the test sample
9 Test methods
9.1 Specification of the reference plane
9.2 Specification of frequencies
9.3 Determination of wavelength and attenuation
9.4 Selection of the signal amplitude
9.5 Determination of the sound absorption coefficient
9.6 Determination of the reflection factor
9.7 Determination of the impedance
9.8 Determination of the admittance
10 Transformation of reflection factor and impedance
11 Test report
Annex A
A.1 Determination of the acoustic centre of the probe microphone
A.2 Determination of the wavelength
A.3 Determination of corrections for the tube attenuation
Annex B
B.1 Verification of the standing wave ratio
B.2 Dynamic range of the probe microphone
B.3 Check of structure-borne excitation of the tube
Annex C
Annex D
Appendix ZZ
Cited references in this standard
Content history
DR 97397