Noise suppression apparatus
First Claim
1. An apparatus for noise suppression of a voice that includes audio and noise, said apparatus comprising:
- main input means for primarily picking up the voice and for outputting an input signal including an audio signal and a first noise component, said first noise component being generated from the noise in the voice;
reference input means for picking up a second noise component generated from the noise in the voice;
filter bank means for band-dividing the input signal from said main input means and the second noise component from said reference input means to output a plurality of divided band components; and
noise cancelling means for obtaining a phase difference between the input signal and the second noise component with respect to each of the divided band components output from said filter bank means so as to correct the input signal based on the phase difference and for cancelling the first noise component in said input signal.
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Abstract
A noise suppression apparatus has a main microphone for mainly picking up a voice and for outputting an input signal including an audio signal and a first noise component generated from a noise source, a reference microphone for picking up a second noise component generated from the noise source, a filter bank for band-dividing the input signal from the main microphone and the second noise component from the reference microphone, and a noise cancel circuit for obtaining a phase difference between the input signal and the second noise component with respect to each divided band of the filter bank so as to correct the input signal based on the phase difference and for cancelling the first noise component in the input signal by use of the corrected input signal.
64 Citations
12 Claims
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1. An apparatus for noise suppression of a voice that includes audio and noise, said apparatus comprising:
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main input means for primarily picking up the voice and for outputting an input signal including an audio signal and a first noise component, said first noise component being generated from the noise in the voice; reference input means for picking up a second noise component generated from the noise in the voice; filter bank means for band-dividing the input signal from said main input means and the second noise component from said reference input means to output a plurality of divided band components; and noise cancelling means for obtaining a phase difference between the input signal and the second noise component with respect to each of the divided band components output from said filter bank means so as to correct the input signal based on the phase difference and for cancelling the first noise component in said input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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7. A noise suppression apparatus as claimed in claim 1 in which said filter bank means has first through Nth linear phase bandpass filters, an ith linear phase bandpass filter band-dividing the input signal Ip=s(t)+n(t) and the second noise component kn(t'"'"') and converting the signals Ip and kn(t'"'"') into time-spectrum patterns for each of N channels, where N is an integer greater than or equal to two and s(t) denotes the audio signal and n(t) denotes the first noise component.
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8. A noise suppression apparatus as claimed in claim 1 in which said filter bank means has first through Nth linear phase bandpass filters, an ith linear phase bandpass filter outputting a time-spectrum pattern ##EQU2## of the input signal Ip and a time-spectrum pattern ##EQU3## of the second noise component kn(t'"'"') responsive to the input signal Ip=s(t)+n(t) and the second noise component kn(t'"'"'), where N is an integer greater than or equal to two, i denotes a channel number, s(t) denotes the audio signal, n(t) denotes the first noise component, k denotes a level difference between the second noise component kn(t'"'"') and the first noise component n(t) which mixes into the audio signal s(t), and t'"'"' denotes a time segment t±
- which takes into account a phase difference between t and t'"'"'.
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9. A noise suppression apparatus as claimed in claim 8 in which said noise cancelling means has a first circuit for detecting the level difference between the second noise component kn(t'"'"') and the first noise component n(t) which mixes into the audio signal s(t) and a second circuit for detecting an audio interval.
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10. A noise suppression apparatus as claimed in claim 9 in which said first circuit obtains an average of the level difference k.
- 11. A noise suppression apparatus as claimed in claim 9 in which said second circuit detects the audio interval from a difference Dd with reference to a threshold value Lth, where Dd=Ds-Dn, Ds and Dn are spectrum differences of the time-spectrum patterns described by
- space="preserve" listing-type="equation">Ds=As(t)-As(t-1)
space="preserve" listing-type="equation">Dn=An(t)-An(t-1).
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12. A noise suppression apparatus as claimed in claim 11 in which said second circuit detects a start of the audio interval when the difference Dd exceeds the threshold value Lth.
Specification