System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech
First Claim
1. A method for removing acoustic noise from speech, comprising the steps of:
- obtaining a speech excitation function using an EM sensor;
identifying a first voiced-excitation onset time from the excitation function;
obtaining an acoustic speech signal, corresponding to the speech excitation function;
subtracting a first predetermined unvoiced time period from the first voiced-excitation onset time to obtain a corresponding first unvoiced-acoustic onset time within the acoustic speech signal;
defining a no-speech time period prior to the first unvoiced-acoustic onset time;
measuring a acoustic noise within the no-speech time period; and
reducing the acoustic noise in the acoustic speech signal.
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Abstract
The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements. entitled “Speech Coding, Reconstruction and Recognition Using Acoustics and Electromagnetic Waves,” issued on Mar. 17, 1998 by Holzrichter et al. These related applications are commonly assigned to The Regents of the University of California, located in Oakland, Calif.
54 Citations
14 Claims
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1. A method for removing acoustic noise from speech, comprising the steps of:
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obtaining a speech excitation function using an EM sensor;
identifying a first voiced-excitation onset time from the excitation function;
obtaining an acoustic speech signal, corresponding to the speech excitation function;
subtracting a first predetermined unvoiced time period from the first voiced-excitation onset time to obtain a corresponding first unvoiced-acoustic onset time within the acoustic speech signal;
defining a no-speech time period prior to the first unvoiced-acoustic onset time;
measuring a acoustic noise within the no-speech time period; and
reducing the acoustic noise in the acoustic speech signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for removing acoustic noise from an acoustic speech signal, comprising the steps of:
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selecting a first set of acoustic speech time frames with timing defined by an excitation function determined using an EM sensor;
characterizing qualities of an acoustic noise signal over a second set of time frames with timing defined by an excitation function determined using the EM sensor and by using the acoustic speech signal over said second set of time frames;
constructing an acoustic noise filter appropriate to the acoustic speech signal over the first set of time frames and to the characterized noise signal over the second set of time frames; and
filtering the acoustic noise signal from the acoustic speech signal over the first set of time frames using the acoustic noise filter. - View Dependent Claims (10, 11, 12, 13)
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14. A system for removing acoustic noise from speech, comprising:
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an EM sensor for generating a speech excitation function from measured movements of a predetermined portion of a vocal tract;
an acoustic sensor receiving an acoustic speech signal, corresponding to the speech excitation function from the vocal tract; and
a computer for, identifying a first voiced-excitation onset time from the excitation function, subtracting a first predetermined unvoiced time period from the first voiced-excitation onset time to obtain a corresponding first unvoiced-acoustic onset time within the acoustic speech signal;
defining a no-speech time period prior to the first unvoiced-acoustic onset time;
measuring acoustic noise within the no-speech time period; and
reducing the acoustic noise in the acoustic speech signal.
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Specification