Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Furnishings and Equipment (hierarchy name)
4. Tools and Equipment (hierarchy name)
5. equipment
6. [equipment by process]
7. [equipment for transmitting and reproducing sound]
8. audio equipment
9. microphones

Anotations

Scope note:

Microphones designed for underwater use. These detect acoustic signals under the water, as conventional microphones pick up signals through the air. Most hydrophones use ceramics that produce electrical current when subjected to changes in underwater pressure, and are normally omnidirectional.