Ambient noise cancellation for voice communications device

• US 8,472,641 B2
• Filed: 10/06/2008
• Issued: 06/25/2013
• Est. Priority Date: 03/21/2002
• Status: Expired due to Fees

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Short, Shannon M., Hartselle, William A., Meadows, Vernon
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): Tran, Con P
• Application Number:
  US12/246,348
• Publication Number:
  US 20090034755A1
• Time in Patent Office: 1,723 Days
• Field of Search: 381/94.1, 381/71.8, 381/92, 381/94.7, 381/120, 381/119, 381/123, 381/122, 381/356, 455/570, 455/569.1, 455/63.1, 455/129, 455/91
• US Class Current: 381/94.1
• CPC Class Codes: G10K 11/17821 characterised by the analysis of the input signals only
• CPC Class Codes: G10K 11/1783 handling or detecting of non-standard events or conditions, e.g. changing operating modes under specific operating conditions
• CPC Class Codes: G10K 11/17857 Geometric disposition, e.g. placement of microphones
• CPC Class Codes: G10K 11/17873 using a reference signal without an error signal, e.g. pure feedforward
• 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: G10K 2210/3036 Modes, e.g. vibrational or spatial modes
• CPC Class Codes: G10K 2210/3045 Multiple acoustic inputs, single acoustic output
• CPC Class Codes: H04M 1/6008 in the transmitter circuit
• CPC Class Codes: H04R 3/002 Damping circuit arrangements for transducers, e.g. motional feedback circuits
• CPC Class Codes: H04R 3/005 for combining the signals of two or more microphones specially adapted for hearing aids H04R25/407

Abstract

A system and method for reducing or entirely canceling background or ambient noise from a voice transmission from a communications device. A communications device, such as a mobile telephone, is configured with an ambient noise compensation signal generator that is connected between a microphone and a mixer. The original output of the microphone and a compensation signal generated by the ambient noise compensation signal generator are mixed together prior to being passed to a transmitter. In one embodiment a buffer is provided between the microphone and the mixer to help synchronize the timing of the signals to be mixed. In another embodiment a second microphone is employed to detect ambient noise.

Claims

1. A communications device, comprising:

a directional first microphone having a microphone output, wherein the directional first microphone is sensitive to sound coming from a predetermined direction such that voice signals are predominantly received by the first microphone;

an omnidirectional second microphone having a microphone output, wherein the second microphone is substantially equally sensitive to sound emanating from any direction, such that voice signals and ambient noise are received by the second microphone;

an ambient noise compensation signal generator having (i) an ambient noise compensation signal generator input connected to the second microphone output and (ii) an ambient noise compensation signal generator output, wherein the ambient noise compensation signal generator is configured to generate a compensation signal;

a mixer having (i) a first mixer input in communication with the first microphone output and (ii) a second mixer input connected to the ambient noise compensation signal generator output and (iii) a mixer output, wherein the mixer is configured to mix the signal from the first microphone output with the compensation signal from the ambient noise compensation signal generator output;

a transmitter having a transmitter input connected to the mixer output and a transmitter output in communication with an antenna, wherein ambient noise picked up by the second microphone is processed by the ambient noise compensation signal generator and wherein the ambient noise is attenuated by the mixer mixing the signal from the first microphone output with the compensation signal before being passed to the transmitter; and

an enable/disable switch for enabling/disabling the ambient noise compensation signal generator, wherein when the ambient noise compensation signal generator is disabled, the output of the second microphone is provided to the mixer as the second mixer input.

2. The communications device of claim 1, wherein the communications device is a mobile telephone.

3. The communications device of claim 1, wherein only the second microphone is in communication with the ambient noise compensation signal generator input.

4. The communications device of claim 1, wherein both the first and the second microphones are in communication with the ambient noise compensation signal generator input.

5. The communications device of claim 1, wherein the second microphone is spatially distant from the first microphone.

6. The communications device of claim 1, further comprising a buffer interposed between the first microphone and the mixer.