Hydrophones

Hydrophones are just like microphones, but designed to detect sounds and vibrations in water and other fluids.
They are usually made of a piezoelectric sensor, that can be cylindrical, flat or spherical, and may have a preamplifier or not. They are usually moulded in a polyurethanic resin, or assembled in another waterproof container. They do their work at best iwhen immersed in a fluid, and they usually perform down to pressures of a 100 bars.
At sea, and in the water in general, they are used to detect acoustic signals. These signals can be man-made (sonars and a million other underwater instruments produce acoustic feedback), can have a biological origin (not only Cetaceans produce underwater signals !), or may have a geological origin, like earthquakes.

On the industrial side hydrophones are used to detect and measure vibrations in pools, pumps, tanks and pipes. Vibration detection is considered an excellent diagnostic tool to follow plant manteinance. On the ecology side hydrophones are a tool to detect and measure the quality and intensity of sounds that man-made activities produce in the water at sea, in lakes and rivers.
This noise can have heavy and hard-to-predict effects not only on cetaceans but on many other animals.
While underwater bioacoustics is mostly known for its studies on Cetaceans, during zoological research hydrophones are used when investigating on Amphibians, Reptiles, Fish and other Mammals too.

◦ Choosing the right hydrophone? read what to consider.
◦ New to hydrophones? No panic, read the hydrophone starter guide.