AT, an Acoustic Transmissometer

The combination of attenuation measurement with acoustic travel-time current measurement along a common path has produced a new acoustic sensor of suspended particles, the acoustic transmissometer (AT). The AT has been deployed in the OASIS experiment, a particle-measuring experiment to determine suspended particle properties resulting from turbulence and current near the seabed. Acoustic transmission at 1.8 MHz, as used in the AT, is a useful complement to optical backscatter or light transmission for assessing particle properties since acoustic transmission loss is the result of acoustic absorption and/or scattering, which depends on particle mass rather than particle area and diameter, as optical measurements do.