Voice activity detector for audio signals

• US 10,586,557 B2
• Filed: 07/19/2019
• Issued: 03/10/2020
• Est. Priority Date: 02/26/2007
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Muesch, Hannes
• Primary Examiner(s): Godbold, Douglas
• Application Number:
  US16/516,634
• Publication Number:
  US 20190341069A1
• Time in Patent Office: 235 Days
• CPC Class Codes: G10L 19/012 Comfort noise or silence coding
• CPC Class Codes: G10L 19/018 Audio watermarking, i.e. embedding inaudible data in the audio signal
• CPC Class Codes: G10L 2025/932 Decision in previous or following frames
• CPC Class Codes: G10L 2025/937 Signal energy in various frequency bands
• CPC Class Codes: G10L 21/02 Speech enhancement, e.g. noise reduction or echo cancellation reducing echo effects in line transmission systems H04B3/20; echo suppression in hands-free telephones H04M9/08
• CPC Class Codes: G10L 21/0364 for improving intelligibility
• CPC Class Codes: G10L 25/78 Detection of presence or absence of voice signals switching of direction of transmission by voice frequency in two-way loud-speaking telephone systems H04M9/10
• CPC Class Codes: G10L 25/93 Discriminating between voiced and unvoiced parts of speech signals G10L25/90 takes precedence

Abstract

According to one aspect, a method for determining voice activity is disclosed, the method including receiving a frame of an input audio signal, the input audio signal having a sample rate, and spitting the audio signal into a plurality of subbands, the plurality of subbands including at least a lowest subband and a highest subband. The method further comprises filtering the lowest subband to reduce an energy of the lowest subband, estimating a noise level for at least some of the plurality of subbands, and computing a signal-to-noise ratio for at least some of the plurality of subbands. The method also includes determining a speech activity level based at least in part on the computed signal-to-noise ratios and an average of an energy of at least some of the plurality of subbands.

Claims

1. A method for determining voice activity in an audio signal, the method comprising:

receiving a frame of an input audio signal, the input audio signal having a sample rate;

spitting the audio signal into a plurality of subbands, the plurality of subbands including at least a lowest subband and a highest subband;

filtering the lowest subband to reduce an energy of the lowest subband;

estimating a noise level for at least some of the plurality of subbands;

computing a signal-to-noise ratio for at least some of the plurality of subbands; and

determining a speech activity level based at least in part on the computed signal-to-noise ratios and an average of an energy of at least some of the plurality of subbands,

wherein the method is performed in an audio encoder with one or more processors.

2. The method of claim 1 further comprising smoothing the computed signal-to-noise ratios over time to create temporally smoothed subband signal-to-noise ratios.

3. The method of claim 1 further comprising determining a weighted average of the computed signal-to-noise ratios as a spectral tilt of the frame.

4. The method of claim 1, wherein the signal-to-noise ratio is computed as a logarithm of a ratio of an energy-to-noise level.

5. An audio processing apparatus for decoding an encoded audio signal, wherein the audio processing apparatus comprises a demultiplexer for unpacking the encoded audio signal and an audio decoder for decoding the encoded audio signal, wherein the encoded audio signal was generated using at least in part the method of claim 1.

6. A non-transitory computer readable medium comprising instructions that when executed by a processor of an audio processing device cause the audio processing device to perform the method of claim 1.