Active noise control headphones

• US 10,410,654 B2
• Filed: 10/27/2018
• Issued: 09/10/2019
• Est. Priority Date: 10/27/2017
• Status: Active Grant

• Current Assignee: Bestechnic (Shanghai) Co., Ltd.
• Original Assignee: Bestechnic (Shanghai) Co., Ltd.
• Inventors: Tong, Weifeng, Xu, Mingliang, Zhang, Liang, Yang, Lei, Zheng, Like
• Primary Examiner(s): Goins, Davetta W
• Assistant Examiner(s): Sellers, Daniel R
• Application Number:
  US16/172,763
• Publication Number:
  US 20190130930A1
• Time in Patent Office: 318 Days
• CPC Class Codes: G10K 11/178 by electro-acoustically regenerating the original acoustic waves in anti-phase
• CPC Class Codes: G10K 11/17853 of the filter
• 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 2210/3039 Nonlinear, e.g. clipping, numerical truncation, thresholding or variable input and output gain
• CPC Class Codes: G10L 2021/02082 the noise being echo, reverberation of the speech
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0264 characterised by the type of parameter measurement, e.g. correlation techniques, zero crossing techniques or predictive techniques
• CPC Class Codes: H04R 1/1041 Mechanical or electronic switches, or control elements switches in general H01H
• CPC Class Codes: H04R 1/1083 Reduction of ambient noise active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06
• CPC Class Codes: H04R 2460/01 Hearing devices using active noise cancellation
• CPC Class Codes: H04R 5/033 Headphones for stereophonic communication details thereof, e.g. relating to batteries, cables or control elements H04R1/10
• CPC Class Codes: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S

Abstract

Embodiments of active noise control (ANC) headphones and operating methods thereof are disclosed herein. In one example, a headphone for ANC includes a speaker, a microphone, an echo-cancel module, and an ANC module. The speaker is configured to play an audio based on a first audio source signal. The microphone is configured to obtain a mixed audio signal including a noise signal and a second audio source signal based on the audio played by the speaker. The echo-cancel module is configured to reduce the second audio source signal from the mixed audio signal based on the first audio source signal to generate an echo-cancel audio signal. The ANC module is operatively coupled to the echo-cancel module and configure to generate a noise-controlled audio source signal to be played by the speaker based on the echo-cancel audio signal and the first audio source signal.

Claims

1. A headphone for active noise control (ANC), comprising:

an external microphone configured to obtain a first talk-through audio signal;

a speaker configured to play an audio based on the first talk-through audio signal;

an internal microphone configured to obtain a mixed audio signal comprising a noise signal and a second talk-through audio signal based on the audio played by the speaker;

an echo-cancel module configured to reduce the second talk-through audio signal from the mixed audio signal based on the first talk-through audio signal to generate an echo-cancel audio signal; and

an ANC module operatively coupled to the echo-cancel module and configure to generate a noise-controlled talk-through audio signal to be played by the speaker, the ANC module comprising;

an ANC filter configured to filter the echo-cancel audio signal to generate a first cancellation signal;

a first adder configured to couple the first cancellation signal and the first talk-through audio signal to generate the noise-controlled talk-through audio signal; and

a first limiter operatively coupled between the ANC filter and the first adder and configured to reduce an amplitude of the first cancellation signal to a first preset level when the amplitude of the first cancellation signal is above a first threshold.

2. The headphone of claim 1, wherein the external microphone is disposed outside an ear canal when the headphone is worn, and the internal microphone is disposed inside the ear canal when the headphone is worn.

3. The headphone of claim 1, wherein the echo-cancel module comprises:

an echo-cancel filter configured to filter the first talk-through audio signal to generate a second cancellation signal; and

a second adder configured to couple the second cancellation signal and the mixed audio signal to generate the echo-cancel audio signal.

4. The headphone of claim 1, wherein

the first limiter has a first signal amplitude threshold, a second signal amplitude threshold, and a third signal amplitude threshold;

and

the first limiter is further configured to;

reduce the amplitude of the first cancellation signal to a value between the first and second signal amplitude thresholds when the amplitude of the first cancellation signal is between the first and third signal amplitude thresholds;

reduce the amplitude of the first cancellation signal to a value of the second signal amplitude threshold when the amplitude of the first cancellation signal is above the third signal amplitude threshold; and

not reduce the amplitude of the first cancellation signal when the amplitude of the first cancellation signal is below the first signal amplitude threshold.

5. The headphone of claim 1, wherein the ANC filter is configured to reduce a gain of the ANC filter when a power of the echo-cancel audio signal is above a threshold.

6. The headphone of claim 1, wherein

the speaker is further configured to play the audio based on a first audio source signal;

the mixed audio signal further comprises a second audio source signal based on the audio played by the speaker;

the echo-cancel module is further configured to reduce the second audio source signal from the mixed audio signal based on the first audio source signal; and

the ANC module is further configured to generate a noise-controlled audio source signal to be played by the speaker based on the echo-cancel audio signal and the first audio source signal.

7. The headphone of claim 1, further comprising:

a talk-through filter configured to filter the first talk-through audio signal; and

a second limiter operatively coupled between the talk-through filter and the echo-cancel module and configured to reduce an amplitude of the filtered first talk-through audio signal to a second preset level when the amplitude of the first talk-through audio signal is above a second threshold.

8. The headphone of claim 1, wherein the ANC filter is a minimum-phase filter with a time delay.

9. The headphone of claim 8, wherein the minimum-phase filter has a sampling rate that balances a power and the time delay of the minimum-phase filter.

10. A method for active noise control (ANC), comprising:

playing, by a speaker, an audio based on a first audio signal;

obtaining, by a microphone, a mixed audio signal comprising a noise signal and a second audio signal based on the audio played by the speaker;

reducing, by a processor, the second audio signal from the mixed audio signal based on the first audio signal to generate an echo-cancel audio signal; and

generating, by the processor, a noise-controlled audio signal to be played by the speaker based on the echo-cancel audio signal and the first audio signal,

wherein reducing the second audio signal from the mixed audio signal comprises;

filtering the first audio signal to generate a first cancellation signal,

reducing an amplitude of the first cancellation signal to a preset level when the amplitude of the first cancellation signal is above a threshold, and

coupling the first cancellation signal and the mixed audio signal to generate the echo-cancel audio signal.

11. The method of claim 10, wherein the first audio signal comprises at least one of a music signal and a talk-through audio signal.

12. The method of claim 11, further comprising obtaining, by another microphone, the talk-through audio signal.