Methods and apparatus for wireless power transfer and communications are provided. In one embodiment, a wireless power transfer system comprises a transmit resonator configured to transmit wireless power, a receive resonator configured to receive the transmitted wireless power from the transmit resonator, a medical device configured to receive power from the receive resonator, a controller configured to change an operating parameter of the medical device resulting in a change to a sonic signature of the medical device, and a listening device configured to determine an intended communication from the implanted medical device or the implanted receive resonator based on the change to the sonic signature coming from the implanted medical device.
