In this last role, he also undertook early experiments into the use of hydrophones to detect submarines.

They are also used militarily to detect submarines.

Underwater acoustics was used for detecting submarines in the first World War.

By December 1940 operational aircraft were detecting submarines at up to 15 miles range.

Active sonar uses the reflection of sound emitted from the search equipment to detect submarines.

And the Navy is actively exploring the possibility of using squids to detect submarines.

During World War I the need to detect submarines prompted more research into the use of sound.

Matthews continued to invent, creating, amongst other things, a machine that was able to detect submarines.

The Coastal class was one of the first aircraft types specifically designed to detect and attack submarines.

He attempted to develop a means of detecting submarines by measuring the disturbance in the Earth's magnetic field.