Method of measuring and analysing wave motion

The method of determining the propagation parameters of wave motion in an acoustical medium has been tested by taking a sample consisting of numerous cylindrical tubes in parallel as a model. Standing and progressive waves in front of and behind the sample in a duct system with a non-reflecting terminal were measured at many frequencies, whence a complete set of propagation parameters was derived.

A refinement of the method has been suggested which serves to eliminate unwanted losses outside the sample, and the achievable improvement in determining the attenuation constant of wave motion in the tube sample is demonstrated and discussed in detail.

The theory of a variant form of the general method is derived which permits a complete set of propagation parameters to be found from resonance curves of the magnitudes of the characteristic factors only.

Experimental results of this novel resonance method and of the extended general method agree well with the corresponding propagation parameters computed with the classical theory.