通过应用主元分析技术建立预报海底沉积物声速的经验方程，将前人研究报道的经验方程进行分析研究，指出其计算误差，运用南海南部大陆架和大陆坡数据，建立了主元回归计算模型。从理论上研究了如何在众多影响声速的物理参数中，排除相互关联的参数，优选出相互独立的、且对声速有显著影响的少数几个物理参数，用优选后的物理参数建立了南海南部海域大陆架及大陆坡沉积物的3参数（孔隙度n、颗粒中值粒径Md、塑限Wp)声速预报方程：Cp =1 774–5.0944n+12.499 Md +0.998 5Wp，该方程的相对预报误差仅为–4.48%—3.77%。

In order to obtain a forecasting equation of sound velocity for seafloor sediments, the authors first apply the technology of principal component analysis and analyze existing empirical equation and its calculation errors. A principle component model is then built up using the measurement data of sediments from the continental slope and shelf in southern South China Sea. The authors also studied in theory how to exclude correlated parameters from a number of parameters that can affect the sound velocity and how to optimize a few parameters that are obviously related to sound velocity without cross-correlation. Using the optimal physical parameters, such as porosity n, median grain size Md and plastic limit Wp, a three-parameter forecasting equation of sound velocity is established for the continental shelf and slope in southern South China Sea. The equation is Cp =1774–5.0944 +12.499 Md +0.9985Wp. The relative forecasting error ranges only from –4.48% to 3.77%.