US Patent 10535364 Voice activity detection using air conduction and bone conduction microphones

A head-mounted wearable device incorporates a transducer that operates as a bone conduction (BC) microphone. Vibrations from a user's speech are transferred through the head of the user to the BC microphone. An air conduction (AC) microphone detects sound transferred via air. Signals from the BC microphone and the AC microphone are compared to determine if a common signal is present in both. For example, both signals may have a cross-correlation that exceeds a threshold value. Based on the comparison, voice activity data is generated that indicates the user wearing the device is speaking.