Statistical properties of the phase difference between the sound pressure and particle velocity

The paper is focused on statistical properties of time derivative of the phase difference between pressure and particle velocity orthogonal projections in the acoustic field composed of a tone or noise-shaped signal and underwater ambient noise in different proportions. The paper does not relate phase difference measurements with oceanological properties of the medium. The paper presents measurements made in shallow water and deep open ocean, and with different proportions between noise and signal. When the exponent averaging time is taken greater than 1 s, mean values of time derivatives approximate zero with different probability densities in different frequency bands.