Comparative evaluation of the speech quality of speech coders and text-to-speech synthesizers

In a joint project called SPIN, which is sponsored by the European Information Technology Program ESPRIT, a speech interface for office automation will be developed and tested. Two specific aspects of such an interface, which are discussed in this paper, have to do with speech store-and-forward and text-to-speech synthesis-by-rule. We will diagnostically evaluate the speech quality of the medium-band coders and of the diphone-based synthesis systems in their various developmental phases from software simulation to hardware prototype. This includes intelligibility, subjective quality, as well as speaker identifiability. Since only native listeners can be used to evaluate the synthetic speech quality of a text-to-speech system in a specific language, we developed a portable, stand-alone, multi-subject system which allows efficient testing on the spot.