A PRACTICAL PROBABILITY EXPRESSION FOR TRANSMITTED SOUND POWER OF A SINGLE WALL IN UNDERWATER TO NON-STATIONARY GAUSSIAN RANDOM NOISE

For the purpose of designing the underwater transmission system using audible sound directly projected by underwater loudspeaker to prevent a diving accident and/or to give a working instruction, it is important to estimate the transmission loss from a wall not only for pure tones but also for wideband signals such as voice and noise. On the other hand, the sound pressure waves of voice signal and noise usually exhibit the non-stationary property with temporal changes of various statistical moments. Furthermore, the sound propagation environment between the sound source and the observation point shows non-stationarity, caused by temporal changes of the sound propagation path, etc. From the above practical viewpoints, in this paper, an approximate expression for the probability density function of transmitted sound power fluctuation is theoretically derived, in the case when a Gaussian-type non-stationary random sound pressure wave with fluctuation of variance is passed through a single wall in underwater. The validity and the usefulness of the theoretical method is confirmed by experiments conducted in a water tank.