Speech quality under heavy noise conditions in hands-free communication
AssigneeContinental Automotive Systems, Inc.
InventorBijal Joshi
Life of this patent
Estimating the term…
Abstract
When the noise in an audio signal made up of both speech and noise is suppressed, the quality of the speech in the audio signal is usually degraded. The speech obtained from a noise-suppressed audio signal is improved by determining linear predictive coding (LPC) characteristics of the audio signal without or prior to noise suppression and by determining the LPC characteristics of the noise-suppressed audio. The convolution of those differing characteristics provides an improved-quality speech signal, with the original noise level reduced or suppressed.
Claims13
A method of improving speech quality in an audio signal comprising speech and noise, after noise in the audio signal is suppressed, the method comprising:
- receiving a first audio signal comprising speech and noise;
- determining characteristics of the first audio signal and generating a linear predictive coding (LPC) representation of said first audio signal;
- providing the first audio signal to a noise suppressor, which is configured to suppress at least some of the noise in the first audio signal and to thereby produce a noise-reduced audio signal;
- generating an error signal using liner predictive coding (LPC) estimation method from the noise-reduced audio signal, the error signal comprising speech in the first audio signal after at least some of the noise in the first audio signal is removed;
- applying the error signal to the LPC representation of the first audio signal to synthesize a second audio signal having a reduced distortion speech and speech quality better than the speech in the first audio signal;
- and
- providing the second audio signal to an audio signal transducer configured to produce audible sound waves from the second audio signal.
A method of improving speech quality in an audio signal after suppressing noise in the audio signal, the method comprising:
- receiving a first audio signal comprising speech and noise, the first audio signal being represented by frames of digital data;
- performing a first partial noise suppression on the first audio signal using to provide a first partial noise-reduced audio signal;
- performing a second partial noise suppression on the first partial noise-reduced audio signal to provide a second noise-reduced audio signal;
- determining a linear predictive coding (LPC) representation of the first partial noise-reduced audio signal;
- generating an error signal from the second noise-reduced audio signal;
- applying the error signal to the LPC representation of the first partial noise-reduced audio signal to synthesize an improved-quality speech signal from the first audio signal;
- receiving a first audio signal comprising speech and noise, the first audio signal being represented by frames of digital data;
- performing a first partial noise suppression on the first audio signal using to provide a first partial noise-reduced audio signal;
- performing a second partial noise suppression on the first partial noise-reduced audio signal to provide a second noise-reduced audio signal;
- determining a linear predictive coding (LPC) representation of the first partial noise-reduced audio signal;
- generating an error signal from the second noise-reduced audio signal;
- applying the error signal to the LPC representation of the first partial noise-reduced audio signal to synthesize an improved-quality speech signal from the first audio signal;
- and
- providing the improved-quality speech signal to an audio signal transducer, which is configured to produce audible sound waves from the time domain improved-quality audio signal.
An apparatus for improving the quality of speech obtained from a first audio signal having speech and noise, after noise in the first audio signal is suppressed, the apparatus comprising:
- a first noise suppressor, configured to:
- suppress at least some of the noise in the first audio signal to thereby produce a noise-reduced first audio signal, the noise-reduced first audio signal comprising distorted speech obtained from the first audio signal;
- a linear predictive code (LPC) analyzer comprising:
- an LPC estimator configured to receive the first audio signal and provide a linear predictive code (LPC) representation of the first audio signal;
- an error signal generator comprising:
- linear predictive code (LPC) estimator configured to generate a linear predictive code (LPC) representation of the noise-reduced first audio signal, after noise in the first audio signal is at least partially suppressed;
- an LPC synthesizer, configured to synthesize speech signals from the LPC representation of the first audio signal and the LPC representation of the audio signal after noise in the first audio signal is at least partially suppressed;
- and
- an audio signal transducer configured to generate audible sound waves. from synthesized speech signals.
Dependencies are inferred from the claim text.