A new application for reverberation tanks: measurement of underwater impulsive sound characteristics

Abstract

A new application for reverberation tanks, used to measure the sound energy of impulsive sound sources, is proposed. According to the law of conservation of energy, the impulsive sound energy obtained by sound intensity integration in the time domain is the same as the sound energy density spectrum obtained by integration in the frequency domain. By utilizing both the multipath incoherent processing technique and invariant sound field correction factors, the energy source level of impulsive sound in a reverberation tank can be obtained, and the measurement methods in the frequency and time domains have both been established. The energy source level of the impulsive sound, on the one hand, is calculated based on the sound energy density spectrum in the frequency domain and, on the other hand, is obtained based on self-correlation in the time domain. Both a sinusoidal impulsive sound experiment and a spark source signal experiment were carried out at UATL (Underwater Acoustics Technology Lab, Harbin Engineering University, China) to confirm the validity of the proposed method. Experimental results showed that the energy source level of the impulsive sounds could be far more precisely measured in reverberation tanks than using free field measurements. The largest deviation was less than 1.1 dB for the impulsive test, and the average deviation was less than 1 dB for the spark source signal test with multiple measurements in different tanks. This study provides a useful method for measuring the characteristics of impulsive signals in reverberation tanks, which greatly extends their range of application.