A mathematical relationship between full-band and multiband mel-frequency cepstral coefficients

Recently, it has been shown that robustness of automatic speech recognition (ASR) against band-limited additive noises may be improved by multiband ASR (MBASR) approaches. In an M-subband MBASR system, the channels in the full-band filterbank are divided into M subbands, usually of equal partitions, and subband mel-frequency cepstral coefficients (MFCCs) are computed from each filterbank partition using the discrete cosine transform. However, there is not as yet any analysis on the relationship between full-band and multiband MFCCs. In this letter, we show that the (Mj)th full-band MFCC is the sum of or difference between the Mjth multiband MFCCs multiplied by /spl radic/M.