Feedforward and feedback headphone acoustic noise cancellation
AssigneeApple Inc.
InventorsTom-Davy W. Saux, Victoria Chiu, Hanchi Chen, Mark Noon, Vladan Bajic
Life of this patent
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Abstract
A processor is configured to determine, using an adaptive filter algorithm, an adaptive feedforward acoustic noise cancellation, ANC, filter, filter a headphone internal microphone signal using a feedback filter to produce a feedback audio signal, drive a headphone speaker with the feedback audio signal, and modify the feedback filter based on a characteristic of the adaptive feedforward ANC filter. Other embodiments are also described.
Claims17
An audio signal processing method for a headphone, the method comprising:
- determining, using a first adaptive filter algorithm, an adaptive feedforward acoustic noise cancellation (ANC) filter, wherein determining the adaptive feedforward ANC filter includes performing the first adaptive filter algorithm using a secondary (S) path estimate, the S path estimate estimating a secondary path transfer function of the headphone as a fixed or time-invariant transfer function;
- filtering an internal microphone signal of the headphone using a feedback filter to produce a feedback audio signal;
- driving a speaker of the headphone with the feedback audio signal;
- and
- modifying the feedback filter based on a characteristic of the adaptive feedforward ANC filter.
A headphone audio apparatus comprising
- a headphone housing having integrated therein a speaker, an internal microphone to produce an internal microphone signal, and an external microphone to produce an external microphone signal;
- and
- a processor configured to:
- determine, using a first adaptive filter algorithm, an adaptive feedforward acoustic noise cancellation (ANC) filter, wherein the processor is configured to determine the adaptive feedforward ANC filter by performing the first adaptive filter algorithm using a secondary (S) path estimate, the S path estimate estimating a secondary path transfer function of the headphone as a fixed or time-invariant transfer function;
- filter the internal microphone signal using a feedback filter to produce a feedback audio signal;
- drive the speaker with the feedback audio signal;
- and
- modify the feedback filter based on a characteristic of the adaptive feedforward ANC filter.
An apparatus for use with a headphone, the apparatus comprising
- a processor configured to:
- determine, using an adaptive filter algorithm, an adaptive feedforward acoustic noise cancellation (ANC) filter, wherein the processor is configured to determine the adaptive feedforward ANC filter by performing the first adaptive filter algorithm using a secondary (S) path estimate, the S path estimate estimating a headphone secondary path transfer function as a fixed or time-invariant transfer function;
- filter a headphone internal microphone signal using a feedback filter to produce a feedback audio signal;
- drive a headphone speaker with the feedback audio signal;
- and
- modify the feedback filter based on a characteristic of the adaptive feedforward ANC filter.
Dependencies are inferred from the claim text.