The acoustic characteristics of small-scale commercial sonars are unlikely to change significantly in the
future since they are limited by several key physical properties. At the low-frequency end (about 3 kHz),
they are limited by the physical dimensions of the transducers. At the high-frequency end (200 kHz) they
are limited by severe attenuation of sound. Likewise, the maximum power level that can be emitted by a single transducer (200 dB re 1µPa @ 1 m) is limited by cavitation at shallow depths of operation. Higher
power levels can be achieved by constructing arrays of sensors on the hull of the vessel. For example,
multibeam echosounding systems (e.g., SeaBEAM or Hydrosweep) form narrow directional beams of
sound and are used for precise depth sounding. Using hull-mounted arrays of transducers, these systems
can achieve 235 dB re 1µPa @ 1 m source levels and are typically operated at 12-15 kHz in deep water,
and at higher frequencies (up to 100 kHz) in shallow water