Discovering Phone Patterns in Spoken Utterances by Non-Negative Matrix Factorization

We present a technique to automatically discover the (word-sized) phone patterns that are present in speech utterances. These patterns are learnt from a set of phone lattices generated from the utterances. Just like children acquiring language, our system does not have prior information on what the meaningful patterns are. By applying the non-negative matrix factorization algorithm to a fixed-length high-dimensional vector representation of the speech utterances, a decomposition in terms of additive units is obtained. We illustrate that these units correspond to words in case of a small vocabulary task. Our result also raises questions about whether explicit segmentation and clustering are needed in an unsupervised learning context.