Described is using the human body as an input mechanism to a computing device. A sensor set is coupled to part of a human body. The sensor set detects mechanical (e.g., bio-acoustic) energy transmitted through the body as a result of an action/performed by the body, such as a user finger tap or flick. The sensor output data (e.g., signals) are processed to determine what action was taken. For example, the gesture may be a finger tap, and the output data may indicate which finger was tapped, what surface the finger was tapped on, or where on the body the finger was tapped.