Abstract: A number of acoustic characteristics of underwater acoustic materials can be evaluated by their complex reflection and transmission coefficients.In this paper,a new method is proposed for the measurements of the performance parameters of finite sized large area material samples in free field by using broadband pulse compression technique,therefor the low-frequency cutoff of the standard tests are obviously reduced.Apart from conventional parameters such as echo reduction and insertion loss,etc,two new anechoic and decoupling coefficients are also assessed.The experimental measurements are performed for two actual panels of about 1m×1 m in the frequency range of 2~20 kHz.