Noun
English Wikipedia has an article on:hydrophoneWikipedia
hydrophone (plural hydrophones)
a transducer that converts underwater sound waves into electrical signals, rather like a microphone
Active sonar is also used to measure distance through water between two sonar transducers or a combination of a hydrophone (underwater acoustic microphone) and projector (underwater acoustic speaker). Source: Internet
Also equipped are a 104 hydrophone hull array and two towed arrays: the TB-12 (later replaced by the TB-16) and TB-23 or TB-29, of which there are multiple variants. Source: Internet
Data is transmitted from the sensors using wireless acoustic telemetry and is received by a hull mounted hydrophone. Source: Internet
Note the teardrop-shaped fairing for the large hydrophone array beneath the bow and the figure-eight pressure hull. Source: Internet
Never having deployed one past a mile, the titanium-shelled hydrophone was designed to withstand the immense pressure 7 miles under. Source: Internet
Sound pressure can be measured using a microphone in air and a hydrophone in water. Source: Internet