MICROPHONE SELECTION PROCESS FOR USE IN A MULTIPLE MICROPHONE VOICE ACTUATED SWITCHING SYSTEM

A microphone selection process is made relatively constant in terms of processing requirements through use of combination values which provide a measure of the quality of the speech signal received in each one of a plurality of microphones. Such combination values are derived in a manner which provides an indication of which one of the plurality of microphones, that provide area coverage for a conference room, for example, best receives the speech signal. In operation, the microphone selection process selects the microphone which best receives the speech signal by comparing a signal energy value received in each one of the microphones to that received in each of the other microphones. More specifically, pairs of microphones are examined, to determine the direction of origin for the speech, by seeking a microphone pair where the speech is strong in the microphone directed toward the source of speech, and weak in an associated microphone directed away from the source of speech. Since a null, which is located at the back of each microphone, is narrower than a main beam or sensitivity pattern, which is located at the front of each microphone, this null is more sensitive to and therefore a better indicator of the direction of origin for the speech than is the main beam. The combination of the signal energy values for each pair of microphones advantageously provides a specific combination value which is used to identify and select the microphone which best receives the speech signal.