US Patent 9363597 Distance-based audio processing for parametric speaker system

A hybrid ultrasonic audio system includes one or more ultrasonic speakers and one or more conventional speakers. An optical imaging system may be used to automatically determine the distance of a listener relative to the audio system. Channel processors apply distance-related transfer function filters to one or more of the audio channels based on the determined distances to equalize the amplitude of the audio played by the ultrasonic speakers relative to the conventional speakers. Channel processors may further apply a phase or time delay to the audio channels to match the phase and time delay of the ultrasonic speaker audio to the conventional speaker audio.