Average acoustic pulse dispersion length in condensed matter channels

Abstract

This paper is concerned with ‘a probing pulse’ propagating in an inhomogeneous condensed state medium. The pulse expands as it travels. This expansion may be correlated to a material-characteristic dimension – such as the size of a grain or of a free path between scattering sites or of a domain – which is a random variable with a mean denoted as g_s . Moreover, we may ascribe to the propagation a loss constant which is proportional to g_s . The process derives from the fact that, for a relatively large number of scattering sites, it is possible to model the propagation media in terms of a repetitive electrical network. The model supports a Gaussian (bell shape) impulse response and defines g_s . Both theoretical and experimental (ultrasonic) results are provided. The experimental method is relatively fast to perform and the results are highly reproducible.

Acknowledgements

The work was supported in part by NIH and by Pile Dynamics Inc. Thanks are also due to Richard Berris for critical comments.