Systems and methods for adaptive active noise cancellation for multiple-driver personal audio device

• US 10,013,966 B2
• Filed: 03/15/2016
• Issued: 07/03/2018
• Est. Priority Date: 03/15/2016
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Kwatra, Nitin, Hendrix, Jon D., Melanson, John L.
• Primary Examiner(s): Monikang, George C
• Application Number:
  US15/070,457
• Publication Number:
  US 20170270906A1
• Time in Patent Office: 840 Days
• Field of Search: 381 711, 381 715, 381 716, 381 717, 381 718, 381 719, 381 7111
• CPC Class Codes: G10K 11/17817 between the output signals and the error signals, i.e. secondary path
• CPC Class Codes: G10K 11/17854 the filter being an adaptive filter
• CPC Class Codes: G10K 11/17879 using both a reference signal and an error signal
• CPC Class Codes: G10K 11/17881 the reference signal being an acoustic signal, e.g. recorded with a microphone
• CPC Class Codes: G10K 11/17885 additionally using a desired external signal, e.g. pass-through audio such as music or speech
• CPC Class Codes: G10K 2210/1081 Earphones, e.g. for telephones, ear protectors or headsets
• CPC Class Codes: H04R 2205/022 Plurality of transducers corresponding to a plurality of sound channels in each earpiece of headphones or in a single enclosure
• CPC Class Codes: H04R 3/12 for distributing signals to two or more loudspeakers specially adapted for hearing aids H04R25/407

Abstract

In accordance with embodiments of the present disclosure, a processing circuit may implement an adaptive filter, a first signal injection portion which injects a first additional signal into a first frequency range content source audio signal, and a second signal injection portion which injects a second additional signal into a second frequency range content source audio signal, wherein the first additional signal and the second additional signal are substantially different. The adaptive filter may have a response that generates the antinoise signal from the reference microphone signal to reduce the presence of the ambient audio sounds at the acoustic output, wherein the response of the adaptive filter is shaped in conformity with the reference microphone signal and the error microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds in the error microphone signal, wherein the antinoise signal is combined with at least the first frequency range content source audio signal.

Claims

1. An integrated circuit for implementing at least a portion of a personal audio device, comprising:

a first output for providing a first output signal to a first transducer for reproducing a first frequency range content source audio signal comprising first frequency range content of a source audio signal, the first output signal including both the first frequency content source audio signal and an antinoise signal for countering the effects of ambient audio sounds in an acoustic output of an earspeaker comprising the first transducer and a second transducer;

a second output for providing a second output signal to the second transducer for reproducing a second frequency range content source audio signal comprising second frequency range content of the source audio signal, the second output signal including at least the second frequency range content source audio signal;

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 earspeaker and the ambient audio sounds at the earspeaker; and

a processing circuit comprising;

an adaptive filter having a response that generates the antinoise signal from the reference microphone signal to reduce the presence of the ambient audio sounds at the acoustic output, wherein the response of the adaptive filter is shaped in conformity with the reference microphone signal and the error microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds in the error microphone signal;

a first signal injection portion which injects a first additional signal into the first frequency range content source audio signal; and

a second signal injection portion which injects a second additional signal into the second frequency range content source audio signal, wherein the first additional signal and the second additional signal are substantially different.

2. The integrated circuit of claim 1, wherein the second output signal includes the second frequency range content source audio signal and the antinoise signal.

3. The integrated circuit of claim 1, wherein:

the second output signal includes the second frequency range content source audio signal and a second antinoise signal for countering the effects of ambient audio sounds in the acoustic output; and

the processing circuit further comprises a second adaptive filter that generates the second antinoise signal from the reference microphone signal to reduce the presence of the ambient audio sounds at the acoustic output, wherein the response of the adaptive filter is shaped in conformity with the reference microphone signal and the error microphone signal by adapting the response of the adaptive filter to minimize the ambient audio sounds in the error microphone signal.

4. The integrated circuit of claim 3, wherein the adaptive filter and the second adaptive filter are adapted at different time intervals.

5. The integrated circuit of claim 3, wherein an adaptation step size of the adaptive filter is substantially different than an adaptation step size of the second adaptive filter.

6. The integrated circuit of claim 1, wherein the processing circuit comprises a feedback filter that generates a feedback antinoise component from the error microphone signal which is combined with a feedforward antinoise component generated by the adaptive filter to generate the antinoise signal.

7. The integrated circuit of claim 1, wherein the first additional signal and the second additional signal are noise signals.

8. The integrated circuit of claim 1, the processing circuit further comprising a crossover filter that generates the second frequency range content source audio signal and the first frequency range content source audio signal from the source audio signal.

9. The integrated circuit of claim 1, the processing circuit further comprising:

a first secondary path estimate filter configured to model an electro-acoustic path of the first frequency range content source audio signal and having a response that generates a first secondary path estimate from the first frequency range content source audio signal;

a first secondary coefficient control block that shapes the response of the first secondary path estimate filter in conformity with the first additional signal and the error microphone signal by adapting the response of the first secondary path estimate filter to minimize the error microphone signal;

a second secondary path estimate filter configured to model an electro-acoustic path of the second frequency range content source audio signal and having a response that generates a second secondary path estimate from the second frequency range content source audio signal; and

a second secondary coefficient control block that shapes the response of the second secondary path estimate filter in conformity with the second additional signal and the error microphone signal by adapting the response of the second secondary path estimate filter to minimize the error microphone signal.

10. The integrated circuit of claim 1, wherein:

the first frequency range content of the source audio signal comprises lower-frequency range content of the source audio signal; and

the second frequency range content of the source audio signal comprises higher-frequency range content of the source audio signal.

11. A method comprising:

generating a source audio signal for playback to a listener;

receiving a reference microphone signal indicative of ambient audio sounds;

receiving an error microphone signal indicative of an output of an earspeaker and the ambient audio sounds at the earspeaker, wherein the earspeaker comprises a first transducer for reproducing a first frequency range content source audio signal comprising first frequency range content of the source audio signal and a second transducer for reproducing a second frequency range content source audio signal comprising second frequency range content of the source audio signal;

adaptively generating an antinoise signal for countering the effects of ambient audio sounds at an acoustic output of the earspeaker by adapting a response of an adaptive filter that filters the reference microphone signal in conformity with the error microphone signal and the reference microphone signal to minimize the ambient audio sounds in the error microphone signal;

injecting a first additional signal into the first frequency range content source audio signal;

injecting a second additional signal into the second frequency range content source audio signal, wherein the first additional signal and the second additional signal are substantially different;

combining the antinoise signal with the first frequency range content source audio signal to generate a first output signal provided to the first transducer; and

generating a second output signal provided to the second transducer, the second output signal including at least the second frequency range content source audio signal.

12. The method of claim 11, further comprising combining the antinoise signal with the second frequency range content source audio signal to generate the second output signal.

13. The method of claim 11, wherein:

adaptively generating a second antinoise signal for countering the effects of ambient audio sounds at the acoustic output by adapting a response of a second adaptive filter that filters the reference microphone signal in conformity with the error microphone signal and the reference microphone signal to minimize the ambient audio sounds in the error microphone signal; and

combining the second antinoise signal with the second frequency range content source audio signal to generate the second output signal.

14. The method of claim 13, further comprising adapting the adaptive filter and the second adaptive filter at different time intervals.

15. The method of claim 13, wherein an adaptation step size of the adaptive filter is substantially different than an adaptation step size of the second adaptive filter.

16. The method of claim 11, further comprising:

generating a feedback antinoise component from the error microphone signal; and

combining the feedback antinoise component with a feedforward antinoise component generated by the adaptive filter to generate the antinoise signal.

17. The method of claim 11, wherein the first additional signal and the second additional signal are noise signals.

18. The method of claim 11, further comprising generating the second frequency range content source audio signal and the first frequency range content source audio signal from the source audio signal with a crossover filter.

19. The method of claim 11, further comprising:

generating a first secondary path estimate from the first frequency range content source audio signal with a first secondary path estimate filter configured to model an electro-acoustic path of the first frequency range content source audio signal;

shaping a response of the first secondary path estimate filter in conformity with the first additional signal and the error microphone signal by adapting the response of the first secondary path estimate filter to minimize the error microphone signal;

generating a second secondary path estimate from the second frequency range content source audio signal with a second secondary path estimate filter configured to model an electro-acoustic path of the second frequency range content source audio signal; and

shaping a response of the second secondary path estimate filter in conformity with the second additional signal and the error microphone signal by adapting the response of the second secondary path estimate filter to minimize the error microphone signal.

20. The method of claim 11, wherein:

the first frequency range content of the source audio signal comprises lower-frequency range content of the source audio signal; and

the second frequency range content of the source audio signal comprises higher-frequency range content of the source audio signal.