Measurement of the acoustical impedance of a black box at low frequencies using a shorter impedance tube
作者:
M. L. Kathuriya,
M. L. Munjal,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1977)
卷期:
Volume 62,
issue 3
页码: 751-754
ISSN:0001-4966
年代: 1977
DOI:10.1121/1.381546
出版商: Acoustical Society of America
数据来源: AIP
摘要:
For the experimental evaluation of the acoustical impedance of a termination by the impedance‐tube method at low frequencies, the length of the impedance tube is a problem. In the present paper, the method of exact analysis of standing waves developed by the authors for the stationary medium as well as for mean flow, has been extended for measurement of the acoustical impedance of a termination at low frequencies. The values of the tube attenuation factor and the wave number at the low frequency of interest are established from the experiment conducted, with the given impedance tube, at a higher frequency. Then, exciting the tube at the desired low frequency it is sufficient to measure sound pressure at three differenct locations (not necessarily the minima) in order to evaluate reflection coefficient and hence the impedance of the termination at that frequency.
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