Signedon receiver: DICTOGRAPH
Inscribedon box, cover and inside: new Acousticon
FunctionThe design of this device dates from circa 1933, when a patent was submitted. In the original patent document of 1936, it is said that "a particular object of the invention is a portable amplifier hearing-aid device having a single actuating grip movable in one direction to energize the operating circuits of the device and successively increase the sound intensity and movable in opposite direction to successively decrease the sound intensity till it reaches a position in which the circuits of the device are de-energized."
"Another particular object of the invention is a portable hearing-aid device which can be easily changed from single-circuit operation without an amplifier to double-circuit operation with an amplifier, and vice versa, and requires only one cord for interconnecting the operating elements of the device."