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Audio Signal Processing

Noise-suppression-apparatus-and-recording-medium-recording-processing-program-for-performing-noise-removal-from-voice

System for set-up of transmitters in high capacity digital radio links

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Noise suppression apparatus and recording medium recording processing program for performing noise removal from voice

Details

Inventors: Takahashi, Hidetaka;
Assignee: Olympus Optical Co., Ltd. (JP)
Primary Examiner: Hudspeth; David R.
Assistant Examiner: Abebe; Daniel
Attorney, Agent or Firm: Ostrolenk, Faber, Gerb & Soffen, LLP

A noise suppression apparatus of the present invention includes a voice/non-voice discriminator for discriminating a frame signal divided into frames having a predetermined length; a Fourier transform unit for converting a frame signal into a spectrum; a noise spectrum estimation unit for estimating a noise spectrum of a frame judged as a non-voice signal; an amplitude spectrum subtractor for subtracting the product of an estimated noise spectrum and a predetermined coefficient from a spectrum obtained by the transform unit; an auditory correction noise adder for adding aa auditory correction noise spectrum to a spectrum outputted from the subtractor; and an inverse Fourier transform unit for performing inverse Fourier transform to an output of the adder. The noise suppression apparatus further includes a negative amplitude value counter for counting the number of frequency components in an output of the subtractor whose amplitude values are negative; a subtraction coefficient setting unit for gradually decreasing a subtraction coefficient unit the counted value becomes not more than a predetermined value; an inverse Fourier transform unit for performing inverse Fourier transform to an output of the counter; and a noise spectrum estimation unit for calculating spectrum information of noise in the frame signal using different spectrum information according to the current type of frame signal.

DETAILED DESCRIPTION A first object of the present invention is to provide a noise suppression apparatus capable of increasing auditory sound quality.
A second object of the present invention is to provide a recording medium for recording a processing program which performs noise removal from a voice signal and is capable of increasing auditory sound quality.
A third object of the present invention is to provide a noise suppression apparatus capable of improving an S/N ratio and increasing auditory sound quality.
A fourth object of the present invention is to provide a recording medium for recording a processing program which performs noise removal from a voice signal and is capable of improving the S/N ratio and increasing auditory sound quality.
A fifth object of the present invention is to provide a noise suppression apparatus capable of improving the S/N ratio and increasing auditory sound quality with simple construction.
A sixth object of the present invention is to provide a recording medium for recording a processing program which performs noise removal from a voice signal and that is capable of improving the S/N ratio and increasing auditory sound quality by simple processing.
Briefly, the present invention is a noise suppression apparatus comprising: a voice discrimination means for discriminating between a voice signal and a non-voice signal in a frame signal which is divided into frames having a predetermined length; a spectrum analysis means for converting the frame signal into a spectrum in the form of a frequency-domain signal; a noise spectrum estimation means for estimating a noise spectrum in a frame that is a non-voice signal discerned by the voice discrimination means; a spectrum subtraction means for subtracting a product by the noise spectrum estimated by the noise spectrum estimation means and a predetermined value from the spectrum obtained by the spectrum analysis means; a spectrum addition means for adding a predetermined spectrum to a spectrum that is an output signal of the spectrum subtraction means; and a time-domain signal conversion means for converting a spectrum, which is an output signal of the spectrum addition means, into a time-domain signal

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