Significance of Emotionally Significant Regions of Speech for Emotive to Neutral Conversion

Most of the speech processing applications suffer from a degradation in performance when operated in emotional environments. The degradation in performance is mostly due to a mismatch between developing and operating environments. Model adaptation and feature adaptation schemes have been employed to adapt speech systems developed in neutral environments to emotional environments. In this study, we have considered only anger emotion in emotional environments. In this work, we have studied the signal level conversion from anger emotion to neutral emotion. Emotion in human speech is concentrated over a small region in the entire utterance. The regions of speech that are highly influenced by the emotive state of the speaker is are considered as emotionally significant regions of an utterance. Physiological constraints of human speech production mechanism are explored to detect the emotionally significant regions of an utterance. Variation of various prosody parameters (Pitch, duration and energy) based on their position in the sentences is analyzed to obtain the modification factors. Speech signal in the emotionally significant regions is modified using the corresponding modification factor to generate the neutral version of the anger speech. Speech samples from Indian Institute of Technology Kharagpur Simulated Emotion Speech Corpus (IITKGP-SESC) are used in this study. A subjective listening test is performed for evaluating the effectiveness of the proposed conversion.