This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
A Comparison of the Transfer and Scattering Matrix Approaches for Determining Muffler Transmission Loss using the Two Load Method
Technical Paper
2015-01-2308
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
The two-load method is commonly applied to determine the transmission loss for a muffler especially if an impedance tube rig is used. Although one procedure and algorithm is detailed in ASTM E2611, the quality of the transmission loss curve is dependent on several factors that are not discussed in detail in the standard. In this paper, several practical concerns are investigated including (1) the number of channels used in the measurement, (2) the selection of the reference channel, and (3) the choice of data processing algorithm (transfer or scattering matrix). Results are compared for a simple expansion chamber first, then for mufflers of other types. Recommendations are made for obtaining smoother transmission loss curves for various measurement methods.
Citation
Zhang, Y. and Herrin, D., "A Comparison of the Transfer and Scattering Matrix Approaches for Determining Muffler Transmission Loss using the Two Load Method," SAE Technical Paper 2015-01-2308, 2015, https://doi.org/10.4271/2015-01-2308.Also In
References
- ASTM E2611-09 Standard Test Method for Measurement of Normal Incidence Sound Transmission of Acoustical Materials Based on the Transfer Matrix Method 2009
- Munjal , M. L. and Doige , A. G. Theory of a Two Source-location Method for Direct Experimental Evaluation of the Four-pole Parameters of an Aeroacoustic Element Journal of Sound and Vibration 141 2 323 333 1990
- Song , B. H. , and Bolton , J. S. A Transfer-Matrix Approach for Estimating the Characteristic Impedance and Wave Numbers of Limp and Rigid Porous Materials J. Acoust. Soc. Am. 107 1131 1152 2000
- Åbom , M. Measurement of the scattering-matrix of acoustical two-ports Mech. Systems and Signal Proc 5 2 89 104 1991
- ACUPRO Measurement System Spectronics Inc. USA www.spectronics.net
- Åbom , M. Derivation of the Four-pole Parameters Including Higher Order Mode Effects for Expansion Chamber Mufflers with Extended Inlet and Outlet Journal of Sound and Vibration 137 3 403 418 1990
- Hua , X. , Zhang , Y. , and Herrin , D. W. The Effect of Conical Adapters and Choice of Reference Microphone when using the Two-Load Method for Measuring Muffler Transmission Loss Applied Acoustics 93 75 87 2015