Apple Inc.

Victoria Chiu

Tom-Davy W Saux

Hanchi Chen

Martin Kuster

Andrew P Bright

Dana C Massie

Vladan Bajic

Brian D Clark

Thomas M Jensen

Disclosed are systems and methods for adaptive noise cancellation (ANC) at a virtual microphone located at the eardrum of a wearer of an earphone. The techniques estimate the level of leakiness of ambient noise in the earphone from the magnitude of the gain of the transfer function of the feed forward loop filter of the ANC. Based on the estimated leakiness, the techniques estimate the transfer function of the feed forward loop filter to compensate for the difference in the effect of noise cancellation at the virtual microphone and error microphone. A bias term that represents the difference in the frequency response of the attenuated noise at the virtual and error microphone may be added to the adaptive feed forward algorithm. The ANC operation may apply the bias term to the adaptive feed forward loop filter to reduce the ambient noise at the eardrum rather than at the error microphone.

Adaptive virtual microphone for earbuds

Disclosed are systems and methods for performing adaptive equalization operations to reduce variations in the frequency response of audio signals at the eardrum of a wearer of an earphone. The assumption that the frequency response of the error microphone matches the frequency response at the eardrum may not be true due to signal leakage effects and the shape of the ear canal. Techniques are disclosed for the adaptive equalization operations to perform a calibration algorithm to compensate for the effects of the signal leakage and the shape of the ear canal. The earphone may estimate the transfer function from the speaker to the error microphone and may estimate the load impedance from the earphone based on a calibrated relationship between the transfer function and the load impedance. The adaptive equalization may use a calibration algorithm to adjust the frequency response at the error microphone to match that at the eardrum.

Adaptive equalization compensation for earbuds

A method for audio signal processing of microphone signals of a headphone. An audio signal from a first microphone of a headphone is filtered by an ANC system to produce a first filtered signal. Dynamic range control is performed upon the first filtered signal to produce a first dynamic range adjusted signal that drives a speaker of the headphone. Other aspects are also described and claimed.

Headphone acoustic noise cancellation and speaker protection or dynamic user experience processing

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San Jose, CA, United States of America

Victoria Chiu