The technology disclosed provides systems and methods for reducing the overall power consumption of an optical motion-capture system without compromising the quality of motion capture and tracking. In implementations, this is accomplished by operating the motion-detecting cameras and associated image-processing hardware in a low-power mode (e.g., at a low frame rate or in a standby or sleep mode) unless and until touch gestures of an object such as a tap, sequence of taps, or swiping motions are performed with a surface proximate to the cameras. A contact microphone or other appropriate sensor is used for detecting audio signals or other vibrations generated by contact of the object with the surface.