PRODUCTION OF AMBIENT NOISE-CANCELLING EARPHONES

摘要

The invention is intended to facilitate the production of ambient noise- cancelling earphones and, to that end, provides a module (30) comprising a microspeaker (34) and an electret microphone (38) both carried on a common substrate (32) which is also configured to incorporate an acoustic resistor (33, 35). The module (30) is incorporated into an earpiece having electrical connections to noise-cancelling electronic circuitry that is provided separately from the earpiece and is housed, for example, in a separate pod (82, 102) or incorporated within the body of a cellular telephone. The performances of the microspeaker (34) and microphone (38) are classified against one or more predetermined operational criteria, enabling the noise-cancelling circuitry to be configured to allow for departures from such criteria. In some embodiments, the module (30) further comprises an information storage device (40) capable of recording data concerning departures from the aforementioned criteria and of providing, upon interrogation, information over the electrical connection to automatically compensate for such departures. The invention also comprises a method of producing ambient noise-cancelling earphones in which the components on the module (30) are classified inter alia by feeding known signals to the microphone (38) and noting the response of the speaker (34) thereto.