Motorcycle stereo audio system with vox intercom

Abstract

An improvement to motorcycle intercom communications between the motorcycle driver and passenger providing for stereo listening in each of both right and left helmet earphones wherein intercom communications may be had through microphones always activated located proximate the mouth of both driver and passenger where when initiating speaking over the microphone, the stereo output of one side of the earphones is reduced by approximately one/half while the stereo output of the other side earphones is terminated completely and the intercom conversation is heard in full over that single side of earphones. Upon the termination of the intercom conversation, the invention circuitry returns both sides of earphones to the pre-existing level of stereo output. The above is accomplished by dividing all sounds which come in over the microphone into a low and high frequency range separated by an audio speaking range wherein the outputs of the low and high frequency range filters are constantly sampled and compared with the energy output of the audio speaking range of frequencies. When the energy in the speaking range of frequencies exceeds the energy in the low and high frequency range, such is indicative that a party is speaking into the microphone and the circuit automatically terminates the output of one earphone, reduces the other by half, and injects the intercom on the earphone whose stereo had been terminated.