An SVD-based scheme for MFCC compression in distributed speech recognition system

This paper proposes a new scheme for low bit-rate source coding of Mel Frequency Cepstral Coefficients (MFCCs) in Distributed Speech Recognition (DSR) system. The method uses the compressed ETSI Advanced Front-End (ETSI-AFE) features factorized into SVD components. By investigating the correlation property between successive MFCC frames, the odd ones are encoded using ETSI-AFE, while only the singular values and the nearest left singular vectors index are encoded and transmitted for the even frames. At the server side, the non-transmitted MFCCs are evaluated through their quantized singular values and the nearest left singular vectors. The system provides a compression bit-rate of 2.7 kbps. The recognition experiments were carried out on the Aurora-2 database for clean and multi-condition training modes. The simulation results show good recognition performance without significant degradation, with respect to the ETSI-AFE encoder.