US Patent 9743170 Acoustic noise reduction audio system having tap control

Acoustic noise reduction (ANR) headphones described herein have current detection circuitry that is used to detect current consumed by ANR circuitry as a result of pressure changes due to a tapping of a headphone. Tapping may be performed to change an audio feature or operating mode. The current detection circuitry senses a characteristic of the current that can be used to determine an occurrence of a tap event. Examples of a characteristic include an amplitude, waveform or duration of the sensed current. Advantageously, the ANR headphones avoid the need for control buttons to initiate the desired changes to the audio feature or operating mode. Error detection circuitry included in the ANR headphones can distinguish between a valid tap events and an occurrence of a different type of event that may otherwise be improperly be interpreted as a tap event.