A model consisting of uniformly distributed concentrated transient sources in closed reverberant systems is used to construct predictions for the diffuse field correlation function and its variance. Such correlations are useful for passive imaging. It is found that the variance is small compared with the square of the mean if estimates are based on a sufficient number of sources, and if a sufficiently long data record is taken from each source. Requirements are predicted to be most onerous at high frequency. Laboratory measurements support this theory. They furthermore indicate that the fidelity of the passively obtained correlation function to an actively obtained waveform depends, not only on having sufficient passive data, but also on an informed compensation for source spectrum and receiver characteristics. It is anticipated that these arguments will be relevant to convergence rates and fidelity for passive imaging in open systems such as are found in seismology and ocean acoustics.
ASJC Scopus subject areas
- Arts and Humanities (miscellaneous)
- Acoustics and Ultrasonics