Noise reduction filter
First Claim
1. A method for enhancing a noisy signal, said noisy signal including a noise element and a signal element, comprising the steps ofpassing said noisy signal through a first adaptive prediction filter so as to obtain a first signal component corresponding to a predictable component of said noisy signal and a second signal component corresponding to a prediction error,passing the first signal component through a first attenuator to obtain a first attenuated signal component,passing the second signal component through a second attenuator to obtain a second attenuated signal component andcombining the first and second attenuated signal components to form an enhanced output signal.
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Abstract
A noise reduction filter for enhancing noisy audio signals, such as speech or music. In accordance with the invention, a noisy signal is passed through a first adaptive prediction filter so as to obtain a first signal component corresponding to the predictable part of the noisy signal and a second signal component corresponding to a prediction error. The first and second signal components are each attenuated respectively, according to the levels of signal and noise in each component, and then recombined to form an enhanced output signal.
119 Citations
28 Claims
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1. A method for enhancing a noisy signal, said noisy signal including a noise element and a signal element, comprising the steps of
passing said noisy signal through a first adaptive prediction filter so as to obtain a first signal component corresponding to a predictable component of said noisy signal and a second signal component corresponding to a prediction error, passing the first signal component through a first attenuator to obtain a first attenuated signal component, passing the second signal component through a second attenuator to obtain a second attenuated signal component and combining the first and second attenuated signal components to form an enhanced output signal.
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12. A method for enhancing a noisy signal, said noisy signal including a noise element and a signal element, comprising the steps of:
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passing said noisy signal through a whitening filter so as to whiten said noise element, passing the output of said whitening filter through a first adaptive prediction filter so as to obtain a first signal component corresponding to the predictable component of said noisy signal and a second signal component corresponding to a prediction error, passing said first signal component through a first attenuator to obtain a first attenuated signal component, passing said second signal component through a second attenuator to obtain a second attenuated signal component, combining said first and second attenuated signal components to form a first output signal, and passing said first output signal through an inverse whitening filter to obtain an enhanced output signal, wherein said whitening filter is adapted dining pauses in said signal element and the coefficients of the inverse whitening filter are determined by the coefficients of the whitening filter.
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13. A method for enhancing a noisy signal, said noisy signal including a noise element and a signal element, comprising the steps of:
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subtracting from said noisy signal an estimate of the predictable part of said noise element so as to obtain a modified noisy signal, passing said modified noisy signal through a first adaptive prediction filter so as to obtain a first signal component corresponding to the predictable component of said noisy signal and a second signal component corresponding to a prediction error, passing said first signal component through a first attenuator to obtain a first attenuated signal component, passing said second signal component through a second attenuator to obtain a second attenuated signal component, combining said first and second attenuated signal components to form a first output signal, and passing said first output signal through an inverse whitening filter to obtain an enhanced output signal. - View Dependent Claims (14)
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15. A noise reduction filter for enhancing a noisy signal, said noisy signal including a noise element and a signal element, said filter comprising:
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a first adaptive prediction filter which is responsive to said noisy signal and produces as outputs a first signal component corresponding to a predictable component and a second signal component corresponding to a prediction error, a first attenuator acting on said first signal component to produce a first attenuated signal component, a second attenuator acting on said second signal component to produce a second attenuated signal component, and a signal combiner for combining the first and second attenuated signal components to form an enhanced output signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A noise reduction filter for enhancing a noisy signal, said noisy signal including a noise element and a signal element, said filter comprising:
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a whitening filter which operates on said noisy signal to produce a modified noisy signal which contain white noise, a first adaptive prediction filter which is responsive to said modified noisy signal and produces as outputs a first signal component corresponding to a predictable component and a second signal component corresponding to a prediction error, a first attenuator acting on said first signal component to produce a first attenuated signal component, a second attenuator acting on said second signal component to produce a second attenuated signal component, a signal combiner for combining the first and second attenuated signal components to form a first output signal, and an inverse whitening filter which operates on said first output signal to produce an enhanced output signal, wherein said whitening filter is adapted during pauses in said signal element and the coefficients of the inverse whitening filter are determined by the coefficients of the whitening filter.
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27. A noise reduction filter for enhancing a noisy signal, said noisy signal including a noise element and a signal element, said filter comprising:
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a subtraction means for subtracting from said noisy speech an estimate of the predictable part of said noise element so as to obtain a modified noisy signal, a first adaptive prediction filter which is responsive to said modified noisy signal and produces as outputs a first signal component corresponding to a predictable component and a second signal component corresponding to a prediction error, a first attenuator acting on said first signal component to produce a first attenuated signal component, a second attenuator acting on said second signal component to produce a second attenuated signal component, and a signal combiner for combining the first and second attenuated signal components to form an enhanced output signal. - View Dependent Claims (28)
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Specification