One of the major difficulties in identifying internal tissue structures with current ultrasonic methods if the lack of quantitative and complete retrieval of the acoustical parameters of tissue by a single technique. Therefore, a mathematical model representing the ultrasonic signal modification by a multilayered tissue mass has been developed to quantify the acoustical transfer function of tissue and characterize each tissue layer on the basis of three acoustical parameters;Two reflected signals from the near and far boundaries of each tissue layer were measured and analyzed by Fourier transform methods to obtain the magnitude ratio of the two signals (acoustical transfer function of each tissue layer). Linear regression on the resultant data and simple mathematical computation yield the tissue acoustical parameters: characteristic impedance, propagation, velocity, and amplitude attenuation coefficient;The results indicate that the proposed model is a valid representation of the acoustical transfer function of tissue for normal incidence of the ultrasonic waves since the acoustical parameters predicted by the proposed model agree with those found in the literature.