"In the study of acoustics, the term ultrasonics is defined as those wave motions that have frequencies greater than about 20,000 cycles per second. The characteristics of a sound wave at any point in a medium can be regarded as completely defined when the amplitude, frequency, and phase of its Fourier components are known.
Sound measurements at their best are difficult. In the last few years sensitive linear microphones and electronic amplifiers have become available. Still, there are two difficulties of prime importance with their use in a sound field. First, there is the precise, absolute calibration of the equipment over a wide range of sound frequencies and intensities. In addition, any detection device whose dimensions are comparable to the wave length of the sound introduces a disturbing effect upon the field of sound itself. Also, there is always the possibility of reflected sound being picked up by the detector.
Intensity or pressure measurement of audible sound and ultrasonic sound contains many experimental errors and great care is necessary in order to secure an accurate determination.
All known measuring devices are limited in that their indications are dependent on the dimensions relative to the wave length of the incident sound. Any type of detector is dependent among other influences on the following factors: (a) wave length of the incident sound, (b) the law of pressure volume variation assumed in the neighborhood of the obstacle, (c) the scattering and diffraction of sound energy from the obstacle.
Most pressure or intensity measuring devices such as radiometers or Rayleigh discs, are inconvenient and laborious to use. Yet, in some types of research work in physics, chemical engineering, and other phases of the physical and biological sciences, it is desirable to measure ultrasonic pressure at various points in liquids. Relative intensity measurements as well as absolute intensity measurements are needed.
It is the purpose of this investigation to design, construct, and calibrate an ultrasonic probe for measuring ultrasonic pressures. With this probe, measurements of the sound pressures in the ultrasonic field can be obtained and the ultrasonic field can be mapped"--Introduction, pages 1-2.
Fuller, Harold Q., 1907-1996
M.S. in Physics
Missouri School of Mines and Metallurgy
iii, 49 pages
© 1957 Robert F. Rohrer, All rights reserved.
Thesis - Open Access
Ultrasonic waves -- Measurement -- Instruments
Scientific apparatus and instruments -- Design and construction
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Link to Catalog Record
Rohrer, Robert F., "A probe for measuring ultrasonic pressures" (1957). Masters Theses. 2563.