Patent ID: 8848933

Claim:
An acoustic signal enhancement device comprising: a memory which stores time-frequency-domain observed signals which are calculated based on acoustic signals observed in the time domain; and circuitry configured to act as: an initializer which sets initial values of parameter estimates that include reverberation parameter estimates, which include regression coefficients used for linear convolution performed for calculating an estimate of reverberation contained in the time-frequency-domain observed signals, source parameter estimates, which include estimates of linear prediction coefficients and prediction residual powers that characterize power spectra of a source signal, and noise parameter estimates, which include one or more noise power spectrum estimates; a first updater which receives the time-frequency-domain observed signals and the parameter estimates for a predetermined observation period, and executes any one of two update processing stages: one updates at least the reverberation parameter estimates for the predetermined observation period; another updates the source parameter estimates for the predetermined observation period, where update in the two update processing stages is done so that a logarithmic likelihood function of the parameter estimates is increased; a second updater which receives at least a part of the parameter estimates updated by the first updater and executes one of the two update processing stages: one updates at least the reverberation parameter estimates for the predetermined observation period; the other updates the source parameter estimates for the predetermined observation period, where the one of the two update processing stages that has not been executed by the first updater is chosen and update in a chosen update processing stage is done so that a logarithmic likelihood function of the parameter estimates is increased; and a checker which checks if a termination condition for the predetermined observation period is satisfied, wherein the linear convolution performed for calculating the estimate of reverberation for each time frame comprising the predetermined observation period includes a linear convolution performed on a plurality of successive time frames which are previous to the time frame; and if the termination condition is not satisfied, a processing in the first updater is executed again for the predetermined observation period and then a processing in the second updater is executed again for the predetermined observation period.