Real-time implementation of HMM-based MMSE algorithm for speech enhancement in hearing aid applications

We describe our recent work on the real-time implementation of a state-of-the-art HMM-based MMSE speech enhancement algorithm, where our earlier published algorithm has been approximated, optimized, and simplified. The key innovations enabling the enhancement system to run in real-time are: (1) an algorithm for automatic selection of the noise model, (2) pruning the MMSE forward calculations, (3) a new pause detection method useable for a SNR down to 0 dB, and (4) task partitioning of the entire system. A preliminary version of the real-time enhancement system is simulated on the IBM-PC 486DX2/66 and at the same time implemented on a DSP platform based on dual TMS320C30 DSP chips using single precision floating point arithmetic.