Howtosignalprocessing
How do underwater hydrophones work?
Just as a microphone collects sound in the air, a hydrophone detects acoustic signals under the water. Most hydrophones are based on a special property of certain ceramics that produces a small electrical current when subjected to changes in underwater pressure.
How is sound used to communicate underwater?
A transducer is attached to the diver's face mask, which converts his or her voice into an ultrasound signal. A fellow diver has an ultrasound receiver, which accepts the signal and converts it back to a sound that the diver can hear, allowing for communication.
