Active noise cancelling device and method of actively cancelling acoustic noise

Patent metadata

Field	Value
Publication number	US-2016171966-A1
Application number	US-201514863228-A
Country	US
Kind code	A1
Filing date	Sep 23, 2015
Priority date	Dec 10, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

An active noise cancelling device including a sensor configured to convert acoustic signals into first audio signals and a speaker acoustically coupled to the sensor A control stage is configured to control the speaker based on the first audio signals to cause the speaker to produce cancelling acoustic waves that tend to suppress acoustic noise components in the acoustic signals. The control stage includes sigma-delta modulator digital filters.

First claim

1 . An active noise cancelling device, comprising:
a sensor configured to convert acoustic signals into first audio signals; a speaker, acoustically coupled to the sensor; and a control stage, configured to control the speaker based on the first audio signals and to cause the speaker to produce cancelling acoustic waves that tend to suppress acoustic noise components in the acoustic signals; wherein the control stage comprises sigma-delta modulator digital filters.

2 . The device according to claim 1 , wherein the sigma-delta modulator digital filters have a transfer function configured to cancel acoustic noise at the sensor.

3 . The device according to claim 2 , wherein the sigma-delta modulator digital filters include a peak filter, a notch filter and a shelf filter.

4 . The device according to claim 1 , wherein the sigma-delta modulator digital filters are in the Cascade-of-Integrators FeedBack form.

5 . The device according to claim 1 , wherein the sigma-delta modulator digital filters comprise respective logarithmic quantizers.

6 . The device according to claim 5 , wherein the logarithmic quantizers are base-2 quantizers.

7 . The device according to claim 1 , wherein at least one of the sigma-delta modulator digital filters has a zero at the Nyquist frequency.

8 . The device according to claim 1 , wherein the first audio signals are in multibit PDM format.

9 . The device according to claim 1 , wherein the control stage comprises a processing module configured to convert a second audio signal received from the sigma-delta modulator digital filters into a third audio signal in PCM format.

10 . The device according to claim 9 , wherein the processing module has a low-pass transfer function and a bandpass gain greater than unity.

11 . The device according to claim 10 , comprising a signal processing stage configured to receive an input signal and to convert the input signal into a fourth audio signal in PCM format.

12 . The device according to claim 11 , wherein the signal processing stage comprises further sigma-delta modulator digital filters.

13 . The device according to claim 12 , comprising a driving stage configured to drive the speaker based on a combination of the third audio signal and fourth audio signal.

14 . An electronic device, comprising:
at least one playback unit, each playback unit including,
a casing;
an acoustic sensor that converts acoustic signals into first audio signals;
a speaker acoustically coupled to the acoustic sensor; and
control stage circuitry being housed within the casing and electrically coupled to the acoustic sensor and the speaker, the control stage circuitry sigma-delta modulator filtering the first audio signals and controlling the speaker based on the filtered first audio signals to generate cancelling acoustic waves that reduce acoustic noise components in the acoustic signals.

15 . The electronic device according to claim 14 , wherein each playback unit is an earpiece.

16 . The electronic device of claim 14 , wherein the at least one playback unit comprises two playback units that form left and right earpieces contained in a headphone assembly.

17 . A method for active noise cancelling, comprising:
converting acoustic signals present in a region into first audio signals; sigma-delta modulator filtering the first audio signals signals to generate acoustic noise cancelling signals; and controlling an acoustic transducer that is acoustically coupled to the region based on the acoustic noise cancelling signals to produce cancelling acoustic waves that tend to suppress acoustic noise components in the acoustic signals.

18 . The method of claim 17 , wherein sigma-delta modulator filtering the acoustic signals to generate acoustic noise cancelling signals comprises peak filtering followed by notch filtering followed by shelf filtering of the acoustic signals.

19 . The method of claim 18 , wherein controlling the acoustic transducer comprises controlling a speaker.

20 . The method of claim 17 , wherein converting acoustic signals present in a region into first audio signals comprises converting acoustic signals present in an ear of a person into the first audio signals.

Assignees

• St Microelectronics Srl
• Stmicroelectronics Shenzhen R&D Co Ltd

Inventors

• Molinari Luca
• Ma Xi Chun
• Feste Sandro Dalle
• Zerbini Martino

Classifications

• H04R3/02

  for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)} · CPC title

• H04R2460/01

  Hearing devices using active noise cancellation · CPC title

• G10K11/1782 Primary

  Physics · mapped topic

• G10K11/17827

  Desired external signals, e.g. pass-through audio such as music or speech · CPC title

• G10K11/17885

  additionally using a desired external signal, e.g. pass-through audio such as music or speech · CPC title