Shallow water acoustic is a topic of much interest in the underwater acoustics community these days, and the geoacoustic parameters are one of the key factors in explaining the acoustic phenomenon. However, the geoacoustic parameters, such as the sound speed and the attenuation coefficient of seabottom, are really very hard to be measured directly, and direct measurement is time-consuming and expensive. So the acoustic inversion method has attracted much attention.

Under the supported of the CAS Knowledge Innovation Program and the National Natural Sciences Foundation of China, ZHANG Xuelei, LI Zhenglin and HUANG Xiaodi of Institute of Acoustics, Chinese Academy of Sciences carried out a series of studies and proposed a hybrid inversion scheme of geoacoustic parameters, which combines dispersion characteristics of normal modes with transmission loss, based on the facts that different parameters have different effects on sound field.

First, considering the dispersion characteristics of normal modes were sensitive to the density and the sound speed of seabottom, and not sensitive to the seabottom attenuation coefficient, the group time delays of different modes and different frequencies were acquired through adaptive optimal kernel time-frequency representation, then the group time delays were taken as the cost function, and using a global optimal algorithm, the seabottom density and the profile of seabottom sound speed were deduced. Successively, the validity of inversion results was evaluated by the a posteriori probability. Last, the attenuation coefficient of sediment is inverted using the transmission loss data recorded from the ship radiation noise. The validity of the total inversion results has been evaluated by making use of the matched field processing source localization.