Abstract: The present disclosure describes an apparatus and a system for generating electrical signals for a loudspeaker. The loudspeaker may include one or more piezoelectric actuators configured to deflect a diaphragm of the loudspeaker in response to an input signal. The apparatus may be configured to receive the input signal and to drive the piezoelectric actuators to deflect the diaphragm based on the received input signal.

Abstract: Audio processing methods and apparatus are provided for at least partially compensating for the Fletcher-Munson effect. An audio processor includes a variable filter receiving an input signal and providing a filtered output signal, the variable filter having a fixed cutoff frequency and a quality factor that is controllable in response to a control signal, and a control circuit configured to detect a signal level representative of input signal level in a selected band and to generate the control signal in response to the detected signal level. The control circuit may include a low-pass band select filter and a detector for detecting a signal level in the band selected by the low-pass filter and for generating the control signal.