Application of Minimum Statistics and Minima Controlled Recursive Averaging Methods to Estimate a Cepstral Noise Model for Robust ASR

Many compensation techniques, both in the model and feature domain, require an estimate of the noise statistics to compensate for the clean speech degradation in adverse environments. We explore how two spectral noise estimation approaches can be applied in the context of model-based feature enhancement. The minimum statistics method and the improved minima controlled recursive averaging method are used to estimate the noise power spectrum based only on the noisy speech. The noise mean and variance estimates are nonlinearly transformed to the cepstral domain and used in the Gaussian noise model of MBFE. We show that the resulting system achieves an accuracy on the Aurora2 task that is comparable to MBFE with prior knowledge on noise. Finally, this performance can be significantly improved when the MS or EMCRA noise mean is reestimated based on a clean speech model