Publication Date

1980

Document Type

Dissertation/Thesis

First Advisor

Rossing, Thomas D., 1929-

Degree Name

M.S. (Master of Science)

Department

Department of Physics

LCSH

Timpani||Membranes (Technology)||Vibration

Abstract

When the frequencies of the tiapani modes of vibration are compared with the frequencies predicted by the theory of an ideal circular membrane, the measured fequencies are spread out. Several factors that may cause this phenomenon are analyzed. Because on the low frequencies characteristic f the timpani vibrations, the stiffness of the membrane is ruled out as a contributing factor. The acoustic properties f the surrounding air are then considered. Resistive damping of the membrane is analysed as a possible cause of the frequency shift. When the decay constants for the timpani are measured, this resistive damping is determined. The measured decay constants indicate that this resistive damping causes negligible shifting of the timpani frequencies. Reactive impedance of the surrounding air is then considered. Assuming that the membrane behaves as a circular piston, an approximation f the reactive impedance can be. made and the effective mass loading of the surrounding air can be calculated. Theoretical wave velocities calculated by considering this effective mass loading are compared with the measured wave velocities. Agreement between these two wave velocities indicates that the effective mass loading is the doainant factor in shifting the frequencies of the timpani.

Comments

Includes bibliographical references.

Extent

vi, 29 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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