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Abstract
Dysarthria is a motor speech disorder that is often associated with irregular phonation (e.g.
vocal fry) and amplitude, in coordination of articulators, and restricted movement of
articulators, among other problems, which causes severe decrease in intelligibility of the
speech for which it is hard to communicate with dysarthic speakers. The aim of this thesis is
to raise automatic dysarthic speech recognition rate through producing intelligibilityenhanced
speech. Procedure used in which formants and energies are estimated from
dysarthic speech and modified to approximately desired normal targets through modification
algorithm which will have two paths. One considered with modifying the formant
information through using voice conversion algorithm based on LPC coefficients
replacement. The other through modification of energy trajectories of dysarthic speech as
well as Fo. The modified parameters are prepared to get the final re-synthesized speech
through a mean that can concatenate the modified formants speech chunk and modified
energy and pitch are taken to formant synthesizer to get final transformed speech, tested
through perceptual tests for ensuring quality and intelligibility, which confirmed an observed
change in positively comprehending the resulting speech from the modification algorithm as
well as speech recognition test using HTK word recognizer. The obtained results indicate
that the applied algorithm enhances intelligibility and raises the recognition rate from 28% to
71.4% also quality of re-synthesized speech increased individuals which indicates