Tsutomu Imai

Dual section electret microphone

A bi-directional capacitor microphone is formed of first and second transducer sections, each section comprising a diaphragm and a back plate facing the diaphragm and separated therefrom. The diaphragm of the first transducer section includes an electret and the back plate of the second transducer section includes another electret. The back plates of the first and second transducer sections are disposed in a back-to-back configuration and are electrically coupled to each other and to one output. The diaphragms of the first and second transducer sections are connected to each other and to another output, so that an output signal appears between the outputs. Preferably, both electrets are selected to have a negative polarity. The bi-directional microphone so constructed exhibits superior response for lower audio frequencies.