Systems and methods for reconstructing an audio signal from transformed audio information

• US 9,177,561 B2
• Filed: 01/09/2015
• Issued: 11/03/2015
• Est. Priority Date: 03/25/2011
• Status: Active Grant

• Current Assignee: Friday Harbor LLC
• Original Assignee: Intellisis Corporation
• Inventors: Bradley, David C., Goldin, Daniel S., Hilton, Robert N., Fisher, Nicholas K., Gateau, Rodney
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): TON, DAVID L
• Application Number:
  US14/593,238
• Publication Number:
  US 20150120285A1
• Time in Patent Office: 298 Days
• Field of Search: 381/94.1, 381/94.4, 381/98, 381/101, 704/E13.004, 704/205, 704/268, 704/200, 704/258, 700/94
• US Class Current: 1/1
• CPC Class Codes: G10L 13/00 Speech synthesis; Text to speech systems
• CPC Class Codes: G10L 19/00 Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis in musical instruments G10H
• CPC Class Codes: G10L 21/00 Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility G10L19/00 takes precedence
• CPC Class Codes: G10L 21/0208 Noise filtering
• CPC Class Codes: G10L 21/0232 Processing in the frequency domain
• CPC Class Codes: G10L 25/45 characterised by the type of analysis window
• CPC Class Codes: G10L 25/90 Pitch determination of speech signals
• CPC Class Codes: G10L 25/93 Discriminating between voiced and unvoiced parts of speech signals G10L25/90 takes precedence
• CPC Class Codes: H03G 5/005 of digital signals
• CPC Class Codes: H03G 5/165 Equalizers; Volume or gain control in limited frequency bands
• CPC Class Codes: H04R 29/00 Monitoring arrangements; Testing arrangements for hearing aids H04R25/30; detection of loudspeaker connection H04R5/04; sound-field adaptation dependent on speaker detection H04S7/308

Abstract

A system and method may be configured to reconstruct an audio signal from transformed audio information. The audio signal may be resynthesized based on individual harmonics and corresponding pitches determined from the transformed audio information. Noise may be subtracted from the transformed audio information by interpolating across peak points and across trough points of harmonic pitch paths through the transformed audio information, and subtracting values associated with the trough point interpolations from values associated with the peak point interpolations. Noise between harmonics of the sound may be suppressed in the transformed audio information by centering functions at individual harmonics in the transformed audio information, the functions serving to suppress noise between the harmonics.

Claims

1. A method for reconstructing an audio signal from transformed audio information, the method comprising:

obtaining transformed audio information representing a sound, wherein the transformed audio information specifies magnitude of a coefficient related to signal intensity as a function of frequency for the audio signal and time;

suppressing noise between harmonics of the sound in the transformed audio information by centering functions at individual harmonics in the transformed audio information, the functions serving to suppress noise between the harmonics to yield noise-reduced transformed audio information, wherein the width of a given function is based on a bandwidth of a corresponding harmonic; and

reconstructing the audio signal based on a reverse transformation of the noise-reduced transformed audio information.

2. The method of claim 1, wherein individual ones of the functions include a Gaussian function, the Gaussian function being configured to suppress information between the harmonics and replace information associated with the harmonics with a Gaussian curve.

3. The method of claim 2, wherein a given Gaussian curve is fitted to a corresponding harmonic.

4. The method of claim 1, wherein individual ones of the functions include a rectangular function, the rectangular function being configured to zero information between the harmonics while preserving information associated with the harmonics.

5. The method of claim 1, wherein the functions are separately applied to real and imaginary components of the transformed audio information.