Handsfree mobile telephone with ambient noise cancelling

摘要

A handsfree communication apparatus, for example a mobile telephone mounted in a vehicle, utilizes a plurality of microphones 12a, 12b to allow simultaneous communication by a plurality of persons. The plurality of microphones 12a, 12b are spaced apart from one another. An amplifier section 32 (or a noise canceller) includes a plurality of operational amplifiers 38, 40 for amplification of the individual signals from the plurality of microphones 12a, 12b and differential amplifier circuit 36 for executing a differential amplification. Through the differential amplification, simultaneously input noise components are canceled out and reduced, and at the same time speech components are extracted. IMAGE