Signedon face of control panel: General Radio Co. / Cambridge Mass.
Inscribedon face of control panel: BEAT FREQUENCY OSCILLATOR / BATTERY OPERATED / TYPE 613-B, SERIAL NO 65
FunctionThis is an oscillator that produces two frequencies that are very close to each other giving rise to the interference effect of beats, where one hears a tone with an oscillating volume. One can adjust the frequency of the main tone throughout most of the hearing range of humans presumably to see the dependence of the perception of beats with frequency. It was used to investigate the perception of hearing in humans.
ProvenanceFrom the Department of Psychology, Harvard University.