Measurement of Interference Structures of Ship-Radiated Noise in Shallow Water with Rock and Sand Bottom

In this study, the interference structures in the frequency domain are measured in the propagation of broadband acoustic waves in shallow water, which are composed of rock and sand bottom. The measured frequency range is from 20 to 2048 Hz, and the receiver is 500m away from a source. As a broadband sound source, ship-radiated noise is employed and a vertical line array, which is composed of 10 hydrophones, serves as a receiver. The result shows that the interference cycle on the rock bottom is 312 Hz shorter than that on the sand bottom. It also shows that as the receiver depth increases, a smaller number of interference peaks appear thus, the interference cycle is longer. This result will be useful in the estimation of bottom properties in shallow water environments. (C) 2011 The Japan Society of Applied Physics