A charging apparatus (102), system (100) and method (500) are provided for charging and/or powering a wearable electronic device, such as electronic eyeglasses. The charging apparatus comprises an acoustic horn, a piezoelectric transducer, and charger circuitry for converting ultrasonic waves received at the horn into a charging signal. The charging signal is used for charging and/or powering the wearable electronic device while the device is being worn.