Analysis and treatment of esophageal speech for the enhancement of its comprehension

This paper resumes an analysis of esophageal speech, and the developing of a method for improving its intelligibility through speech synthesis. Esophageal speech is characterized by low average frequency, while the formant patterns are found to be similar of those of normal speakers. The treatment is different for voiced and unvoiced frames of the signal. While the unvoiced frames are hold like in the original speech, the voiced frames are re-synthesized using linear prediction. Various models of vocal sources have been tested, and the results were better with a polynomial model. The fundamental frequency is raised up to normal values, keeping the intonation.