BANDLIMITING ANTI-NOISE IN PERSONAL AUDIO DEVICES HAVING ADAPTIVE NOISE CANCELLATION (ANC)
First Claim
1. A personal audio device, comprising:
- a personal audio device housing;
a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer;
a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds;
an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and
a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, wherein a response of the anti-noise signal to the reference microphone signal has an additional shaped frequency response independent of the adapting to alter the anti-noise signal component of the acoustic output of the transducer as heard by the listener.
1 Assignment
0 Petitions
Accused Products
Abstract
A personal audio device, such as a wireless telephone, includes noise canceling circuit that adaptively generates an anti-noise signal from a reference microphone signal and injects the anti-noise signal into the speaker or other transducer output to cause cancellation of ambient audio sounds. An error microphone may also be provided proximate the speaker to measure the output of the transducer in order to control the adaptation of the anti-noise signal and to estimate an electro-acoustical path from the noise canceling circuit through the transducer. A processing circuit that performs the adaptive noise canceling (ANC) function also either adjusts the frequency response of the anti-noise signal with respect to the reference microphone signal, and/or by adjusting the response of the adaptive filter independent of the adaptation provided by the reference microphone signal.
-
Citations
43 Claims
-
1. A personal audio device, comprising:
-
a personal audio device housing; a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, wherein a response of the anti-noise signal to the reference microphone signal has an additional shaped frequency response independent of the adapting to alter the anti-noise signal component of the acoustic output of the transducer as heard by the listener. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
-
first measuring ambient audio sounds with a reference microphone to produce a reference microphone signal; second measuring an output of the transducer and the ambient audio sounds at the transducer with an error microphone; adaptively generating an anti-noise signal from a result of the first measuring and the second measuring for countering the effects of ambient audio sounds at an acoustic output of the transducer by adapting a response of an adaptive filter that filters an output of the reference microphone; combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer; and shaping a frequency response applied to the generated anti-noise signal independent of the adapting of the response of the adaptive filter to reduce error between an anti-noise signal component of the acoustic output of the transducer as heard by the listener and an anti-noise signal component of the acoustic output of the transducer. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
-
an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds; an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds in the error microphone signal, wherein a response of the anti-noise signal to the reference microphone signal has an additional shaped frequency response independent of the adapting to alter the anti-noise signal component of the acoustic output of the transducer as heard by the listener. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
-
-
29. A personal audio device, comprising:
-
a personal audio device housing; a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements an adaptive filter having a response that generates the anti-noise signal from the reference microphone signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit shapes the response of the adaptive filter in conformity with the error microphone signal and the reference microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds at the error microphone, wherein the response of the adaptive filter is further adjusted independent of the adapting, in order to constrain the adaptive filter to alter the adapting of the adaptive filter to the ambient audio sounds. - View Dependent Claims (30, 31, 32)
-
-
33. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
-
first measuring ambient audio sounds with a reference microphone to produce a reference microphone signal; second measuring an output of the transducer and the ambient audio sounds at the transducer with an error microphone; adaptively generating an anti-noise signal from a result of the first measuring and the second measuring for countering the effects of ambient audio sounds at an acoustic output of the transducer by adapting a response of an adaptive filter that filters an output of the reference microphone; combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer; adjusting a response of the adaptive filtering independent of the adaptively generating, in order to constrain the adaptive filter to alter the adapting of the adaptive filter to the ambient audio sounds; and providing a result of the combining to the transducer to generate the acoustic output. - View Dependent Claims (34, 35, 36)
-
-
37. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
-
an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds; an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements an adaptive filter having a response that shapes the anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener, wherein a response of the adaptive filter is adjusted independent of the adaptation of the adaptive filter to the ambient audio sounds, in order to constrain the adaptive filter to alter the adapting of the adaptive filter to the ambient audio sounds. - View Dependent Claims (38, 39, 40)
-
-
41. A personal audio device, comprising:
-
a personal audio device housing; a transducer mounted on the housing for reproducing an audio signal including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone mounted on the housing for providing a reference microphone signal indicative of the ambient audio sounds; an error microphone mounted on the housing in proximity to the transducer for providing an error microphone signal indicative of the acoustic output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements a filter having a fixed frequency response and an adjustable gain that adjusts a magnitude of the anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit adjusts the gain of the filter to minimize the ambient audio sounds at the error microphone.
-
-
42. A method of canceling ambient audio sounds in the proximity of a transducer of a personal audio device, the method comprising:
-
first measuring ambient audio sounds with a reference microphone to produce a reference microphone signal; second measuring an output of the transducer with an error microphone and the ambient audio sounds at the transducer; adaptively generating an anti-noise signal from a result of the first measuring and the second measuring for countering the effects of ambient audio sounds at an acoustic output of the transducer by adjusting a gain of a filter that filters an output of the reference microphone; combining the anti-noise signal with a source audio signal to generate an audio signal provided to the transducer; and providing a result of the combining to the transducer to generate the acoustic output.
-
-
43. An integrated circuit for implementing at least a portion of a personal audio device, comprising:
-
an output for providing a signal to a transducer including both source audio for playback to a listener and an anti-noise signal for countering the effects of ambient audio sounds in an acoustic output of the transducer; a reference microphone input for receiving a reference microphone signal indicative of the ambient audio sounds; an error microphone input for receiving an error microphone signal indicative of the output of the transducer and the ambient audio sounds at the transducer; and a processing circuit that implements a filter having a fixed frequency response and an adjustable gain that adjusts a magnitude of the anti-noise signal to reduce the presence of the ambient audio sounds heard by the listener, wherein the processing circuit adjusts the gain of the filter to minimize the ambient audio sounds at the error microphone.
-
Specification