Backscatter

Acoustic backscatter refers to the component of sound waves emitted by a sonar that are reflected from the seabed back in the direction from which they came. The intensity of backscattered energy depends on a number of factors including the angle of incidence of the acoustic beam, the acoustic wavelength, and the ‘roughness’ or scattering properties of the seabed. Backscatter intensity is measured in decibels (dB re 1uPa @ 1 m). In general, a higher backscatter represents a harder or rougher substrate than an area with a lower backscatter. Typically, acoustic backscatter is only useful as a relative measurement, therefore comparison of datasets from different water depths or acquired using different sonar parameters is extremely problematic.