Formant re-synthesis of dysarthric speech

Dysarthria is a motor speech disorder that is often associated with irregular phonation (e.g. vocal fry) and amplitude, incoordination of articulators, and restricted movement of articulators, among other problems. The present study is part of a project on voice transformation systems for dysarthria, with the goal of producing intelligibility-enhanced speech. We report on a procedure in which formants and energies are estimated from dysarthric speech; next, these trajectories are modified to more closely approximate desired targets; finally, transformed speech is generated using formant synthesis. Results indicate that the transformation step enhances intelligibility, and that removal of vocal fry enhances perceived quality. However, the initial step of stylizing the formant trajectories results in a decrement in intelligibility, thereby reducing the net impact of the process.