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)
6. [sound devices by acoustical characteristics]
7. electrophones
8. electronic instruments
9. electronic keyboards

Anotations

Scope note:

Monophonic, nonimitative electronic instruments, invented by Maurice Martenot in 1928. The tone is generated by the heterodyne action between a fixed and a variable radio-frequency oscillator, the latter being controlled by a seven-octave keyboard and the relative proximity of the player's hand to a horizontally stretched cord.