Improvements in acoustic tomography

An array of acoustic transducers is arranged around an area of interest such as a water tank and each transducer in turn transmits pulses of sound signals which are received by each of the other transducers. The area is notionally sub-divided into a square grid cell being traversed by at least one sound path between transducers. The acoustic characteristics can be determined for each cell and used to measure temperature and/or to detect gas bubbles in a fluid from sound propagation velocity and attenuation. (author)