Patent ID: 8731909
Filing Date: 2014-05-20
Classification: G10L

Abstract:
1. A spectrum smoothing apparatus comprising: a time-frequency transformation section that performs a time-frequency transformation of an input signal and generates a frequency component; a subband dividing section that divides the frequency component into a plurality of subbands; a representative value calculating section that calculates, for each subband, a representative value by calculating an arithmetic mean and by using a multiplication calculation using the arithmetic mean; a non-linear transformation section that performs a non-linear transformation of representative values of the subbands; and a smoothing section that smoothes the representative values subjected to the non-linear transformation in the frequency domain, wherein the representative value calculating section calculates the representative values of the subbands by dividing each subband into a plurality of subgroups, calculating an arithmetic mean value per subgroup, and calculating, for each subband, the geometric mean of the arithmetic mean values of the subgroups corresponding to the subband as the representative value of the subband.