Masters Theses


"Noise measurements were made near the exhaust of three small pneumatic tools operating under various loads and with various components removed. One-third octave analyses were performed on the noise for identification of noise sources and to determine possible noise reduction techniques. It was determined that the noise spectra consisted of broad band turbulent flow noise plus periodic components at the tool motor blade passage frequency and harmonics of this frequency. One tool, the nut setter, was selected for reverberant field noise analyses and noise reduction studies. Reverberant field measurements indicated that most of the tool noise was transmitted through the tool body; however, exhaust noise reduction studies were conducted to determine possible muffler configurations for better exhaust noise attenuation with less back pressure than the standard muffler. Similar designs could be used for attenuation of both exhaust noise and tool body radiated noise. Three experimental mufflers evaluated included a modified expansion chamber, a modified resonator, and a modified double expansion chamber. The modified expansion chamber provided very good attenuation, but produced considerable back pressure. The modified resonator tested did not provide acceptable attenuation at low tool speed; however, a possible method for improvement is given. The modified double expansion chamber provided relatively good attenuation over a broad range of tool speeds. Recommendations are made for further muffler studies, and for further studies of body radiated noise. Possible methods of approach for further work are suggested"--Abstract, page ii.


Gatley, William S.

Committee Member(s)

Rocke, R. D. (Richard Dale), 1938-
Davis, Robert L.


Mechanical and Aerospace Engineering

Degree Name

M.S. in Mechanical Engineering


University of Missouri--Rolla

Publication Date



ix, 82 pages

Note about bibliography

Includes bibliographical references (pages 60-61).


© 1970 Phillip Ray Elam, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Pneumatic tools -- Noise
Noise control -- Testing

Thesis Number

T 2343

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Electronic OCLC #