Noise suppressor having weighted gain smoothing
First Claim
Patent Images
1. A noise suppressor comprising:
- a signal to noise ratio (SNR) determiner adapted to determine the SNR per channel of an input signal; and
a gain smoother adapted to produce a smoothed gain {overscore (γ
ch+L (i,m))} for the ith channel, wherein said smoothed gain {overscore (γ
ch+L (i,m))} is a function of a previous gain value {overscore (γ
ch+L (i,m−
1+L ))} for an ith channel and a forgetting factor α
which is a function of the current level of said SNR for said ith channel, said forgetting factor α
ranges between MAX_ALFA and MIN_ALFA according to the function where σ
(i,m) is the SNR of the current frame m of the ith channel and SNR_DR is the allowed dynamic range of the SNR.
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Abstract
A noise suppressor is provided which includes a signal to noise ratio (SNR) determiner, a channel gain determiner, a gain smoother and a multiplier. The SNR determiner determines the SNR per channel of the input signal. The channel gain determiner determines a channel gain γch(i) per the ith channel. The gain smoother produces a smoothed gain {overscore (γch+L (i,m))} per the ith channel and the multiplier multiplies each channel of the input signal by its associated smoothed gain {overscore (γch+L (i,m))}.
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Citations
8 Claims
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1. A noise suppressor comprising:
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a signal to noise ratio (SNR) determiner adapted to determine the SNR per channel of an input signal; and
a gain smoother adapted to produce a smoothed gain {overscore (γ
ch+L (i,m))} for the ith channel,wherein said smoothed gain {overscore (γ
ch+L (i,m))} is a function of a previous gain value {overscore (γ
ch+L (i,m−
1+L ))} for an ith channel and a forgetting factor α
which is a function of the current level of said SNR for said ith channel, said forgetting factor α
ranges between MAX_ALFA and MIN_ALFA according to the functionwhere σ
(i,m) is the SNR of the current frame m of the ith channel and SNR_DR is the allowed dynamic range of the SNR.- View Dependent Claims (2, 3)
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4. A noise suppressor comprising:
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a channel gain determiner adapted to determine a channel gain γ
ch(i) per ith channel; and
a gain smoother adapted to produce a smoothed gain {overscore (γ
ch+L (i,m))} for the ith channel,wherein said smoothed gain {overscore (γ
ch+L (i,m))} is set to be either the channel gain γ
ch(i) or a new value, wherein said new value is provided only if the channel gain γ
ch(i) for the current frame m is greater than the smoothed gain {overscore (γ
ch+L (i,m−
1+L ))} for the previous frame m−
1.- View Dependent Claims (5)
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6. A noise suppressor comprising:
a selector adapted to select between a channel gain γ
ch(i) and a smoothed gain {overscore (γ
ch+L (i,m))}, said smoothed gain {overscore (γ
ch+L (i,m))} is selected when said channel gain γ
ch(i) of a received frame m is greater than the smoothed gain {overscore (γ
ch+L (i,m−
1+L ))} for a previous frame m−
1.- View Dependent Claims (7, 8)
Specification