This paper reports our recent efforts to develop a uni£ed, non-linear, stochastic model for estimating and removing the effects of additive noise on speech cepstra. The complete sys- tem consists of prior models for speech and noise, an observa- tion model, and an inference algorithm. The observation model quanti£es the relationship between clean speech, noise, and the noisy observation. Since it
... [Show full abstract] is expressed in terms of the log Mel- frequency £lter-bank features, it is non-linear. The inference algorithm is the procedure by which the clean speech and noise are estimated from the noisy observation. The most critical component of the system is the observa- tion model. This paper derives a new approximation strategy and compares it with two existing approximations. It is shown that the new approximation uses half the calculation, and pro- duces equivalent or improved word accuracy scores, when com- pared to previous techniques. We present noise-robust recogni- tion results on the standard Aurora 2 task.