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 demonstrate the interference of sound, consisting of two U-tubes, one sliding into the other, with a Galton's whistle at one intersection of the tubes and a sensitive flame at the other. Air passes through the two bends of the tube to meet at the flame, and the flicker is analyzed against a scale on one of the tubes.