New Method for Finite‐Amplitude Wave Analysis

A new method for the measurement of the frequency components of a finite‐amplitude wave has been devised which makes use of fixed‐distance measurements. A 2‐transducer pulse technique has been developed so that the problems of alignment and traversal of the transducers can be eliminated. The method has been used to determine the fundamental‐frequency component as a function of distance in the near field of a 5‐Mc pulse‐operated transducer in water for various initial pressures. The measurements are shown to yield results observed by other investigators; in addition, some other results are obtained. For example, there is a definite tendency for the finite‐amplitude effect to limit the maximum sound‐pressure amplitude which can be propagated over a given distance. In addition, it is found that it is incorrect to extrapolate curves of pressure vs distance to the transducer face from measurements made at a distance. The method is most useful for small values of the parameter αL [William W. Lester, J. Acoust. ...