Assessment of Acoustic Nonlinearity Parameters Using an Optimized Data-Fitting Method with Multi-Gaussian Beam Model-Based Diffraction Corrections

摘要

This article presents a novel approach to determine the nonlinearity parameter using an optimized data fitting method. Based on the quasilinear theory of the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, the fundamental and second harmonic pressure fields are expressed using multi-Gaussian beam (MGB) models which separate attenuation and diffraction effects from the plane wave solutions. The developed diffraction corrections are used with a curve-fitting method to extract the nonlinearity parameter together with other acoustic parameters including the attenuation coefficients at the fundamental and second harmonic frequencies. The source nonlinearity is also considered in the fitting process. The proposed scheme is validated through experiments in water and shows that a reliable nonlinearity parameter can be acquired within the range of suitable input power that satisfies the quasilinear approximation involved.