Noise removing apparatus and noise removing method

A noise removing method, comprising:

• carrying out an object sound emphasis process for observation signals of first and second microphones disposed in a predetermined spaced relationship from each other to produce an object sound estimation signal;
• carrying out a noise estimation process for the observation signals of the first and second microphones to produce a noise estimation signal;
• removing noise components remaining in the object sound estimation signal by a post filtering process using the noise estimation signal;
• calculating, for each frequency, a correction coefficient for correcting the post filtering process to be carried out based on the object sound estimation signal and the noise estimation signal;
• and
• changing those of the correction coefficients which belong to a frequency band which suffers from spatial aliasing such that a peak which appears at a particular frequency is suppressed.

A noise removing apparatus, comprising:

• an object sound emphasis section adapted to carry out an object sound emphasis process for observation signals of first and second microphones disposed in a predetermined spaced relationship from each other to produce an object sound estimation signal;
• a noise estimation section adapted to carry out a noise estimation process for the observation signals of said first and second microphones to produce a noise estimation signal;
• a post filtering section adapted to remove noise components remaining in the object sound estimation signal produced by said object sound emphasis section by a post filtering process using the noise estimation signal produced by said noise estimation section;
• a correction coefficient calculation section adapted to calculate, for each frequency, a correction coefficient for correcting the post filtering process to be carried out by said post filtering section based on the object sound estimation signal produced by said object sound emphasis section and the noise estimation signal produced by said noise estimation section;
• an ambient noise state estimation section adapted to process the observation signals of said first and second microphones to produce sound source number information of ambient noise;
• and
• a correction coefficient changing section adapted to smooth the correction coefficient calculated by said correction coefficient calculation section in a frame direction such that the number of smoothed frames increases as the number of sound sources increases based on the sound source number information of ambient noise produced by said ambient noise state estimation section to produce changed correction coefficients for the frames.

A noise removing method, comprising:

• carrying out an object sound emphasis process for observation signals of first and second microphones disposed in a predetermined spaced relationship from each other to produce an object sound estimation signal;
• carrying out a noise estimation process for the observation signals of the first and second microphones to produce a noise estimation signal;
• removing noise components remaining in the object sound estimation signal by a post filtering process using the noise estimation signal;
• calculating, for each frequency, a correction coefficient for correcting the post filtering process to be carried out based on the object sound estimation signal and the noise estimation signal;
• processing the observation signals of the first and second microphones to produce sound source number information of ambient noise;
• and
• smoothing the correction coefficient in a frame direction such that the number of smoothed frames increases as the number of sound sources increases based on the sound source number information of ambient noise to produce changed correction coefficients for the frames.

A noise removing apparatus, comprising:

• an object sound emphasis section adapted to carry out an object sound emphasis process for observation signals of first and second microphones disposed in a predetermined spaced relationship from each other to produce an object sound estimation signal;
• a noise estimation section adapted to carry out a noise estimation process for the observation signals of said first and second microphones to produce a noise estimation signal;
• a post filtering section adapted to remove noise components remaining in the object sound estimation signal produced by said object sound emphasis section by a post filtering process using the noise estimation signal produced by said noise estimation section;
• a correction coefficient calculation section adapted to calculate, for each frequency, a correction coefficient for correcting the post filtering process to be carried out by said post filtering section based on the object sound estimation signal produced by said object sound emphasis section and the noise estimation signal produced by said noise estimation section;
• a first correction coefficient changing section adapted to change those of the correction coefficients calculated by said correction coefficient calculation section which belong to a frequency band which suffers from spatial aliasing such that a peak which appears at a particular frequency is suppressed;
• an ambient noise state estimation section adapted to process the observation signals of said first and second microphones to produce sound source number information of ambient noise;
• and
• a second correction coefficient changing section adapted to smooth the correction coefficient calculated by said correction coefficient calculation section in a frame direction such that the number of smoothed frames increases as the number of sound sources increases based on the sound source number information of ambient noise produced by said ambient noise state estimation section to produce changed correction coefficients for the frames.