Frequency Modulation Technique for Prosodic Modification

Abstract

Modulation of speaking tone in frequency can make speech interesting and convey subtle meaning in communication. We present a frequency modulation (FM) technique for prosodic modification to consider communicative speech synthesis. This technique provides a mathematical formulation for representing speaking tone and manipulating FM in a unified framework. Two experiments are conducted with a text-to-speech system to which a module of FM-based prosodic modification is added. One is to enhance emphasis in words when synthesizing Chinese conversational speech. The other is to modify readingstyle prosody while conveying good and bad news in Japanese; this is done by using the FM technique to shift the frequency ranges and rescale the fundamental frequency contours jointly. The experimental results indicated that the native speakers identified 90% of samples with emphases and 78% of "good news" as well as 94% of "bad news" samples. The FM technique is vital for making synthetic speech communicative.