Directional hydrophone

Directional hydrophone

Typical directional hydrophone applications involve the positioning of a hydrophone on the ocean floor or parallel to a boat under the water’s surface. Sound waves travelling in from a distance will reach the directional hydrophone at different times, and the time differences help find the source of signal waves by the ‘triangulation point’, minimising continuous ambient ocean sounds. Marine environmental researchers deploy directional hydrophone arrays to track underwater marine life and behavioural patterns.

Submarines also deploy directional hydrophone applications to track the location of remotely operated vehicles (R.O.V) to avoid collision. The directional hydrophone is placed on top of a submarine, facing downwards between roughly 25 to 30 degree angle to the hull of the surface vessel, which allows for an exact tracking system. By tracking the incoming boat, the submarine crew can stay in a safe place underwater until the surface area is clear to avoid colliding with the surface vessel. Likewise, this allows the crew of the surface vessel to resume course without collision with the R.O.V.

Whale & Dolphin Recordings:

Additional applications for a hydrophone include: Environmental monitoring, navigation / positioning systems, underwater exploration, towed arrays, deep ocean opperation and many more.


The applications of ocean bottom hydrophones are now becoming extremely useful in tracking patterns of micro-earthquakes and subterranean volcanic activity. They have much helped to measure the increase in seismic activity over several years to the point at which a volcanic eruption can now be predictable.


Hydrophone sensitivity through varying water temperature

The temperature of water will also affect how efficiently sound travels through it. Warmer surface water is less dense, therefore sound travelling through such water to the surface will refract and thus become trapped. This reaction is known as a ‘surface duct’. Due to the fact that most hydrophones are used in open water environments, they are constantly exposed to temperature and pressure fluctuations. This can cause major issues, so the technology needs to be configured to account for these variations to give exact data of sound signals.

In order to measure sensitivity of an open water hydrophone, the electrical changes are considered upon the choice and application of a hydrophone sensor. The impedance can be determined by observing sinusoidal signal equipment. The overall solution is to carry out calibration tests of the transducers in expected environmental conditions, and/or to substitute with more compatible equipment if necessary.