Pitch in Emotional Speech and Emotional Speech Recognition Using Pitch Frequency

Variations of speech parameters due to emotion or stress are noticeable. In the presence of such variations, if a neutral model is used for the system, the speech recognition accuracy deteriorates. The evaluation of how emotion influences speech parameters is the first step towards emotional speech recognition. Pitch frequency is an important parameter in speech processing systems. Therefore in this research the effect of pitch frequency and its slope due to emotion is explored for voiced phonemes. On the other hand, the influence of emotional state on continuous speech recognition performance is evaluated. The results show that the recognition performance of sentences with angry and happiness states and also interrogative sentences has the most deterioration. This deterioration is more than 68% when compared to neutral speech recognition accuracy. To improve recognition results, we add the pitch frequency information to the end of speech recognizer feature vector. The amount of improvement depends on the type of emotion and also added pitch information. The results show that, pitch frequency slope has a significant affect on the improvement of speech recognition accuracy even for neutral speech.