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Introduction Acoustics analysis plays a prominent role in the measurement of speech intelligibility of dysarthric speech disturbances. Vowels produced by speakers exhibiting the dysarthria associated with Stroke are characterized by abnormalities that can be detected at the perceptual, physiological, and acoustical levels of analysis. Vowel space area (VSA) refers to the two-dimensional area bounded by lines connecting ﬁrst and second formant frequency coordinates (F1/F2) of vowels. Aim & Objectives The present study aimed to determine the Formant Centralization Ratio (FCR3) and Vocalic Anatomical Functional Ratio (VAFR) among the individuals with dysarthria and normal population in Malayalam. The main objective of the study was to document the formants (F1, F2, F3) among individuals with dysarthria ( 5 Males & 5 Females) and typical adults ((15 Males and 15 Females) between the ages 18 to 40 years. Method The phonation samples of phonemes /a/,/i/,/u/ were obtained with a high quality condenser microphone at a distance of 12cm away from the mouth. The stimuli were further analyzed with Praat software. The frequencies of the first three formants were used to extract the function of Vowel Space area. The frequency values were used to create vowel quadrilateral plots, including F1-F2, F1-F3. FCR3 is the inverse of vowel articulation index (VAI3) deduced with the formula which was given by Sapir, Ramig, Spielman and Fox in 2010. The following formulas were used to derive the selected parameters. Formant Centralization Ratio (FCR3) = (F2u + F2a +F1i +F1u) ÷ (F2i + F1a). Vocal Anatomical Function Ratio = (F2i /F2u). Results & Discussions Results suggested that there was significant difference of Formant values of phoneme /i/ between the groups. Formant frequencies (F1 & F2) of phoneme /i/ correlates with the height and advancement of the tongue in the production of the vowel. Other formant values were not significant. Formant Centralization Ratio (FCR3) was significantly different with a statistical significance level of 0.11 between the groups in Independent samples Kruskar Wallis test. The values of VFR were not statistically different among the group. Conclusion It was a preliminary attempt in the study to articulatory deficits in individuals with dysarthria. Perceptually, vowels are considered to be distorted, which is hypothesized to be the result of physiological deficits such as weakness in orofacial structures (i.e., especially the tongue) and/or reductions in the range and speed of articulatory movements. The acoustic correlate of the articulatory deficits in individuals with dysarthria are indicated in the new measures namely with Formant Centralization Ratios and Vocalic Anatomical Function Ratio.
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