Average Radiation-pressure Forces Produced by Sound Fields

Abstract

SummaryRadiation-pressure forces developed within an acoustic system may be calculated from a detailed knowledge of the fields. It is shown that the time average of a generalized radiation-pressure force may be expressed in terms of quantities on an arbitrary mathematical surface enclosing the system.The resulting surface integral is related to directly measurable circuit-theory parameters involving the impedance, admittance, or scattering matrices of the system. These results are the same as those obtained previously for electromagnetic systems (Smith 1961(Smith , 1964. The system must be linear and free of energy loss mechanisms but there is no limitation to the frequency of excitation.

Basic Consideration of Inverse Problems for Vocal Tract Deformation from Non-Uniform Tube

“…(29) n n E E Schroeder [5] discussed an inverse problem of predicting the shape of vocal tract for utterance of a sound. He formulated the inverse problem by using Boltzmann-Ehrenfest's theorem [7,8] for a uniform vocal tract with the constant cross sectional area and showed that the solution of the problem is not unique. This means that we need some constraint conditions to make the problem unique.…”

“…In the pioneering works [6,7] the relationship between the vocal tract shape and the formant frequencies was discussed under these rules. Schroeder [5] derived a very useful perturbation formula by using Boltzmann-Ehrenfest's theorem [8,9] for the adiabatic invariance. In this formula, the increase in the formant frequency is proportional to the acoustic radiation pressure on the vocal tract wall where a constriction is made.…”