A wide-band method for sound speed and attenuation measurement in sediments

Marine sediments exist universally as the lower boundary for sound propagation in ocean waveguides, and knowledge of the properties of sediments is important for accurate modeling of sound propagation and reverberation. In order to measure sound speed and attenuation in sediments fast and accurately, a method based on pulse compression technique is proposed, where transmission wave is extracted from the received compressing signal. The sound speed and attenuation were measured according to transmission wave through different thicknesses of samples. This method not only can overcome unavoidable multi-path disturbance in experiment, but also can easily obtain the sound speed and attenuation for different frequencies in measured frequency band at the same time. That is, wide-band measurement for sound speed and attenuation is realized. In laboratory environment, the measured sound speed in the sand sample is 1710~1713 m/s and the attenuation is 56~70 dB/m in the frequency range of 90~170 kHz. Through the comparison of narrow and wide-band results, it is found that the sound speed measured by wide-band method agrees well with that of narrow-band method, while the attenuation exhibits large fluctuation at the second half of measured frequency band.