Exemplar-based Sparse Representation phone identification features

Exemplar-based techniques, such as k-nearest neighbors (kNNs) and Sparse Representations (SRs), can be used to model a test sample from a few training points in a dictionary set. In past work, we have shown that using a SR approach for phonetic classification allows for a higher accuracy than other classification techniques. These phones are the basic units of speech to be recognized. Motivated by this result, we create a new dictionary which is a function of the phonetic labels of the original dictionary. The SR method now selects relevant samples from this new dictionary to create a new feature representation of the test sample, where the new feature is better linked to the actual units to be recognized. We will refer to these new features as S_pif. We present results using these new S_pif features in a Hidden Markov Model (HMM) framework for speech recognition. We find that the S_pif features allow for a 2.9% relative reduction in Phonetic Error Rate (PER) on the TIMIT phonetic recognition task. Furthermore, we find that the S_pif features allow for a 4.8% relative improvement in Word Error Rate (WER) on a large vocabulary 50 hour Broadcast News task.