Speech Synthesis for Distance Cueing in Audio Displays

The work proposed in this Phase II STTR project is aimed at developing (1) a prototype speech synthesizer capable of manipulating the vocal effort of speech for use in text-to-speech synthesis, and (2) a prototype real-time system dedicated to modifying the apparent vocal effort of an arbitrary speech signal input. These two technical objectives will be achieved by (1) thorough acoustic analysis of the reference corpus of speech collected in Phase I; (2) using synthetic and modified speech to manipulate individual acoustic parameters likely to be cues for vocal effort changes related to distance, such as duration changes in vocalic and consonantal portions of speech; and (3) conducting psychoacoustic testing of the synthetic and modified speech to identify the important and necessary acoustic cues for distance based on vocal effort. Identification of these cues will lead directly to improved synthesis rules and modification algorithms for the prototype systems which are being based on existing products to minimize software and hardware development efforts. The availability of these systems will enable inclusion of realistic cues for talker distance in auditory displays and virtual environments.