An Optimized Model for Visual Speech Recognition Using HMM

Visual Speech Recognition (VSR) is to identify spoken words from visual data only without the corresponding acoustic signals. It is useful in situations in which conventional audio processing is ineffective like very noisy environments or impossible like unavailability of audio signals. In this paper, an optimized model for VSR is introduced which proposes simple geometric projection method for mouth localization that reduces the computation time.16-point distance method and chain code method are used to extract the visual features and its recognition performance is compared using the classifier Hidden Markov Model (HMM). To optimize the model, more prominent features are selected from a large set of extracted visual attributes using Discrete Cosine Transform (DCT). The experiments were conducted on an in-house database of 10 digits [1 to 10] taken from 10 subjects and tested with 10-fold cross validation technique. Also, the model is evaluated based on the metrics specificity, sensitivity and accuracy. Unlike other models in the literature, the proposed method is more robust to subject variations with high sensitivity and specificity for the digits 1 to 10. The result shows that the combination of 16-point distance method and DCT gives better results than only 16-point distance method and chain code method