earphone systems and methods for automatically directing ambient sound to an earphone device are provided . an ambient microphone signal from an ambient microphone proximate a sound isolating earphone or headset device is directed to a receiver within an earphone device according to mixing circuitry . the mixing circuitry is controlled by voice activity of the earphone device wearer . this enables hands - free operation of an earphone system to allow the earphone device wearer to maintain situation awareness with the surrounding environment . during detected voice activity , incoming audio content is attenuated while ambient sound is increased and provided to the earphone device . user voice activity is detected by analysis of at least one of an ear canal microphone signal or an ambient sound microphone signal .