@2010Speech and Speaker RecognitionIntroductionSpeech is the most vital form of transferring information and hence a lot of effort has been made in order to deal with hindrances to its production. Speeches vary according to their structure. The presence of dedicated researchers has led to various discoveries and innovative ways to address the quality of communication. In this work, speech errors, methods of analysis as well as examples are all used to bring out the true nature of speech and as well as providing a stepping stone from which evidence could be gathered about the speech related issues. Dysarthic speech recognitionDysarthia as a family of neurogenic speech disorders affects almost the complete speech sub-system like laryngeal, velopharyngeal and the articulary subsystems.
Dysarthric problems are as a result of the muscular control disruption because of the peripheral’s or even central nervous system’s lesions which results in the disruption of the message transmission for effective movement through motor controls, due to these complications it can also be grouped under the neuromotor disorder (Enderby, 1983). It varies in intelligibility as well as rate of production. Even though there are various aspects in the dysarthric complications that can be considered, however this part will deal with approaches and the analysisApproachesThere are various speech recognition approaches employed in dealing with the dysarthic speech including the automatic speech recognition system which is essential in the assessment of the dysarthic speech, the Sy and Horowitz’s model (1) for determining the link between judgment from naïve listeners and the dynamic time warping response.
discrete hidden Markov models is inaccurate and therefore not suitable for the disarthic assessment (Pidal et al. ). Dysarthia assessment using the intelligible metric have also been considered by Charmichael and green.
The continuous speech recognition system performance is correlated with the frenchise dysarthic assessment hence its application in this assessment (Luettin 1997). Assessment Dysarthia –related problems are mostly in the form of acoustic variations from the normal speech. The speech recognition system can be applied for the assessment if the relationship between the variation and speech recognition performance system is captured. The main issue is to get the acoustic variation for the assessment (Chin-Hui & Soong 1996). The systems used Continuous speech recognition systemThis is developed for the assessment of dysarthic speech.
The problems encountered while testing arthritic speech include the invariability among the different arthritic speakers and negative accuracy due to the greater insertion numbers. Although there is correct recognition of the number of phonemes, it also has a setback of lack of correlation between the response of continuous speech recognition system and the arthritic speech. Extent and location of damage could affect the prolongation of the phoenemes as the duration analysis between the normal and dysarthic speech below shows.
Dysarthric speech1 Accuracy = 100 −deletion + substitution + insertion percent Total number of phonemes 2. Duration d = 1 1 − aiiDurational analysisComputation of duration of each phoneme for each speaker is computed from the time aligned phonetic transcription. The phonemes duration of the dysarthric speakers is always higher than those for normal speakers indicating the elongation of phoneme duration of the dysarthric speakers than that of normal speakers. The duration provides information about the intelligibility of the dysarthric speakers. normaluzed variance of duration of phonemes ranges from 3-20 times in greatness than the normal speech.
The table below highlights the variance and intelligibility scores from. Column 1 of table 1shows the ratings of dysarthirc speakers while the mark * indicates the speakers with uncorrelation in variance and intelligibility scores.