A model-based approach for <i>B/A</i> estimation using the finite amplitude insertion-substitution method

An enhanced, model-based framework is presented for estimating the acoustic nonlinearity parameter B/A using the finite amplitude insertion-substitution (FAIS) method in transmission mode. The proposed approach advances harmonic amplitude modeling by eliminating the restrictive plane wave assumption and introducing shape functions that accurately account for transducer diffraction and wave superposition. Additionally, a correction term for second-harmonic attenuation is incorporated, enabling precise characterization across a wide range of attenuation exponents. The framework supports both iterative and direct B/A estimation methods, each validated through comprehensive simulations and experimental measurements. Compared to conventional FAIS methods, this method significantly improves accuracy and robustness in B/A estimation, reduces sensitivity to experimental setup and transducer geometry, and provides practical guidance for optimizing experimental parameters such as sample thickness, distance between source, sample, and receiver, and attenuation measurement.