A method comprising generating a mechanical signal in a mammal, the mechanical signal having a frequency no more than 50,000 Hz, transmitting the mechanical signal through the musculoskeletal system in the mammal, and sensing the mechanical signal from the musculoskeletal system. A method of triggering an internal event comprising generating a mechanical signal internal or external to a mammal, transmitting the signal through the musculoskeletal system of the mammal, detecting the mechanical signal, and triggering an event in response to the mechanical signal. A method of drug delivery comprising generating a mechanical signal internal or external to a mammal, transmitting the signal through the musculoskeletal system of the mammal, detecting the mechanical signal, and delivering the drug in response to the mechanical signal.