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On the length scale and Strouhal numbers for sound transmission across coupled duct cavities at low Mach number

Tang, S. K.; Tang, Yijia


Yijia Tang


The sound transmission across two coupled cavities along a rectangular duct in the presence of a low Mach number flow is examined experimentally in the present study. An effort is also made for a deeper understanding of how the flow, excitation sound frequency, and excitation level influence the sound transmission loss. The results confirm that the high sound transmission loss across the cavities is associated with the strong out-of-phase pressure fluctuations within the cavities. The sound transmission loss deteriorates significantly once the flow speed exceeds a threshold value. A different length scale is proposed. This length scale, together with the threshold flow speed and the peak sound transmission loss frequency, gives a Strouhal number, which is basically independent of the cavity offset for a fixed cavity length. The present finding extends the previous effort of the authors, enabling the prediction of the flow speed limit and operating frequency of the coupled cavities for duct silencing at a low Mach number.


Tang, S. K., & Tang, Y. (2021). On the length scale and Strouhal numbers for sound transmission across coupled duct cavities at low Mach number. The Journal of the Acoustical Society of America, 150(6), 4232-4243.

Journal Article Type Article
Acceptance Date Nov 15, 2021
Online Publication Date Dec 9, 2021
Publication Date 2021-12
Deposit Date Jul 11, 2022
Publicly Available Date Jul 27, 2022
Journal Journal of the Acoustical Society of America
Print ISSN 0001-4966
Electronic ISSN 1520-8524
Publisher Acoustical Society of America
Peer Reviewed Peer Reviewed
Volume 150
Issue 6
Pages 4232-4243
Public URL


Accepted manuscript (2.3 Mb)

Copyright Statement
Copyright 2021 Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.

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