Hierarchy classification:

1. top of the aat hierarchies
2. Objects Facet
3. Furnishings and Equipment (hierarchy name)
4. Sound Devices (hierarchy name)
5. sound devices (equipment)

Anotations

Scope note:

Instruments used to study human sensitivity to changes in pitch. Originally invented by William Stern in 1897 for psychological research. These consist of a brass resonator tube that is supplied with a flow of air across its top end while an interior piston may be raised or lowered, or in some cases mercury introduced, changing the volume of the chamber, thus altering the pitch of the tone of the resonator. A circular scale attached to the front indicates the audible resonance frequency.