Noise estimation apparatus, the noise estimation method, the noise estimating program, and recording medium

The noise component that changes every moment to provide a noise estimation device for estimating at maximum likelihood criterion. Noise estimation apparatus uses the complex spectrum of a plurality of observation signals of the frames up to the current, and the logarithmic likelihood and the speech presence posterior probability of the model of the observed signal of the speech presence intervals represented by Gaussian distribution for each frame multiplication value and a value sum to the weighted addition of the multiplied value of a model log likelihood and the sound absence posterior probability of the observed signal of the speech absence interval represented by Gaussian distribution for each frame, larger as noise determining a variance value of the signal.