Patent ID: 7702505

Claim:
A channel normalization apparatus for robust speech recognition, comprising: a characteristic extraction unit extracting mel-frequency cepstrum coefficient (MFCC) characteristics from a received input speech signal, and wherein the extracted MFCC characteristics for a frame of the receive input speech signal is output in rows of the frames according to time; a characteristic parameter average calculation unit calculating an average value of the rows of the outputted MFCC characteristics; a channel variation estimation unit for each frame, wherein a codebook of MFCC characteristics are configured from a database of speech signals with attenuated channel variations and estimating a channel variation for each frame by calculating a distance between a MFCC parameter for each frame and a median value of the codebook when a MFCC parameter is generated of a channel having a distorted input speech signal; and a smoothing operation based channel normalization unit configured to perform a smoothing operation to a second average value of the channel variation obtained from the characteristic parameter average calculation unit and the channel variation for each frame obtained from the channel variation estimation unit, subtracting the second average value from the MFCC value of each frame, and outputting rows of channel normalized MFCC characteristics.