Acoustic dispersion and attenuation measurement using both transmitted and reflected pulses

Traditional broadband transmission method for measuring acoustic dispersion and attenuation requires the measurement of the thickness of the specimen. the transmission coefficient at the water-specimen interface, and the Fourier spectra of two transmitted pulses. A new method has recently been developed that can determine both the thickness and dispersion of the specimen by utilizing the phase spectra of two additional pulses reflected back from the front and back surfaces of the specimen. In this paper, the method is further extended to the measurement of attenuation. If the density of the specimen is known. the frequency-dependent transmission coefficient can be determined based on the measured phase velocity, and only the amplitude spectra of the two transmitted pulses are used to determine the attenuation. If the density of the specimen is unknown, the attenuation can be determined from the amplitude spectra of all the four pulses. In both cases, the thickness estimated from the phase spectra of the four pulses is utilized. Experimental results from two specimens are presented to demonstrate the application of the new method. (C) 2001 Elsevier Science B.V. All rights reserved.