Masters Theses


"In the following report, a method for evaluating the attenuation characteristics of a general muffler as well as the design, construction and use of the associated apparatus are described. The method combines accepted plane wave theory and experimental techniques into a relatively straightforward approach to the analysis of acoustic filters. Equations are developed to cover the frequency range between 300 and 4000 cycles per second. Deviations from these equations extend the use of the equipment to low frequencies without the need for unduly long and cumbersome apparatus. This method, which may be called the standing wave method, utilizes a standing wave tube with a sliding microphone pickup to determine the reflection characteristics of a given termination. then, the reflection characteristics so determined are used with data collected in a transmission tube apparatus to determine the transmission characteristics of the termination. The experimental analysis of a variable length expansion chamber is compared to its theoretically determined characteristics to demonstrate the usefulness of the equipment. An auto muffler, which is not amenable to theoretical analysis, is then analyzed experimentally over the frequency range of interest. The analysis is discussed and compared to the noise spectrum measured at the end of the tailpipe for the same type of muffler mounted on an automobile. Certain errors which are inherent in the experimental equipment or procedure are pointed out and their effect on the data is estimated whenever possible. Recommendations for the improvement of the apparatus are made"--Abstract, page viii-ix.


Gatley, William S.

Committee Member(s)

Cunningham, Floyd M.
Keith, Harold D. (Harold Dean), 1941-


Mechanical and Aerospace Engineering

Degree Name

M.S. in Mechanical Engineering


National Science Foundation (U.S.)
University of Missouri at Rolla. Department of Mechanical Engineering


University of Missouri at Rolla

Publication Date



ix, 105 pages

Note about bibliography

Includes bibliographical references (pages 89-92).


© 1967 Stephen Philip Buckley, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Equalizers (Electronics) -- Design and construction
Internal combustion engines -- Mufflers
Wave equation

Thesis Number

T 2063

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