Hybrid Speech Recognition Systems: a Real Alternative to Traditional Approaches?

In this paper, an introduction to hybrid modeling techniques for speech recognition is presented. A hybrid speech recognition system consists of the combination of Hidden Markov Models (HMMs) with Neural Networks (NNs) in order to combine the advantages of these two powerful pattern recognition techniques for improved speech recognition. An overview of several different hybrid speech recognition approaches is presented, and special emphasis is given to the establishment of relationships between these different techniques and traditional speech recognition techniques. In this way, it is demonstrated that all popular speech recognition techniques are more or less related to each other, but that hybrid approaches can still be considerd to be an interesting alternative to traditional techniques and will take an important role in future speech technology research.