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Assessing speech intelligibility in a group of Egyptian dysarthric patients




Improving speech intelligibility in dysarthric patients is considered the primary goal of therapeutic intervention.


This study aimed at examining factors affecting speech intelligibility in four Arabic-speaking dysarthric groups using perceptual and instrumental techniques in order to gain a better understanding of the important factors contributing to reduced speech clarity in these patients.

Methods and procedures

Participants included 30 male Egyptian dysarthric patients (patient group) and 30 male age-matched healthy individuals (control group). The patient group was subdivided–on the basis of the neurological examination and investigation that had been carried out previously at the Neurology Department, Kasr el Aini Hospital–into four subgroups; spastic, ataxic, flaccid, and hypokinetic (having Parkinsonism). Speech samples consisting of spontaneous speech and a standard reading passage (that the participants were asked to repeat after the assessor) were used to obtain the following variables: speech rate (number of words per minute), Speech Intelligibility Score, number of nonintelligible words per minute, dysphonia grade, percent of consonants correct, percent of vowels correct, Nasalance Score, fundamental frequency, jitter, shimmer, harmonic-to-noise ratio, duration of /a/, first and second formant frequency values for three corner vowels /a/, /i/, and /u/, voice onset time of /b/, /t/, /k/, stop gap of /t/, /t/, /d/, /d/, and duration of /s/ and /∫/. The study examined the differences between the healthy control group and the different dysarthric groups for each variable as well as the correlation between speech intelligibility and each variable within each dysarthric subgroup.

Outcomes and results

The Speech Intelligibility Score was the highest for flaccid dysarthria and the lowest for ataxic. Results revealed significant differences between the control group and each of the patient groups studied for all subjective measures as well as most of the instrumental measures that were included in the study. A significant positive correlation was found between speech rate and speech intelligibility in patients with ataxic and flaccid dysarthria. However, a negative correlation was found between speech rate and speech intelligibility in patients with hypokinetic dysarthria. A significant negative correlation was found between speech intelligibility and jitter, F1 and F2 of /u/, stop gap of /t/, /t/, /d/, and /d/, and /s/ duration in spastic, ataxic, and flaccid groups. In addition, a significant negative correlation was found between shimmer and speech intelligibility in the ataxic group and between Nasalance Score and speech intelligibility in the flaccid group.

Conclusion and implications

Factors contributing to reduced speech intelligibility vary from one type of dysarthria to the other.


  1. Kent RD. Hearing and believing: some limits to the auditory-perceptual assessment of speech and voice disorders. Am J Speech Lang Pathol. 1996; 5: 7–23

    Article  Google Scholar 

  2. Shipley KG Assessment in speech–language pathology: a resource manual. San Diego, CA: Singular Pub. Group; 1992.

    Google Scholar 

  3. Gerralt B, Til J, Rosenbek J, Wertz R, Boysen A. In: Pauh H, editor. Use and perceived value of perceptual and instrumental measure in dysarthria management. Baltimore: Brookes Publishing Company; 1991.

  4. Mary GB. Assessing intelligibility: children’s expressive phonologies. Top Lang Disord. 1994; 14: 17–25

    Article  Google Scholar 

  5. Yorkston KM, Breukelman DR. Communication efficiency of dysarthric speakers as measured by sentence intelligibility and speaking rate. J Speech Hear Disord. 1981; 46: 296–301

    Article  CAS  Google Scholar 

  6. Hartelius L, Runmarker B, Andersen O. Prevalence and characteristics of dysarthria in a multiple-sclerosis incidence cohort: relation to neurological data. Folia Phoniatr Logop. 2000; 52: 160–177

    Article  CAS  Google Scholar 

  7. Kent RD, Kent JF, Duffy JR, Thomas JE, Weismer G, Stuntebeck S. Ataxic dysarthria. J Speech Hear Res. 2000; 43: 1275–1289

    Article  CAS  Google Scholar 

  8. Hardcastle WJ, Gibbon F. Electropalatography and its clinical applications. In Ball MJ, Code C, editors. Instrumental clinical phonetics. London: Singular Pub. Group; 1997. pp: 149–193

    Chapter  Google Scholar 

  9. Caruso AJ, Burton EK. Temporal acoustic measures of dysarthria associated with amyotrophic lateral sclerosis. J Speech Hear Res. 1987; 30: 80–87

    Article  CAS  Google Scholar 

  10. Conder E An investigation of fundamental frequency, maximum frequency phonation range, frequency perturbation and pathological phonation Independent study. Hunter College. New York City, USA: Institute of Electrical and Electronic Engineers; 1988.

    Google Scholar 

  11. Kent RD, Rosenbek JC. Prosodic disturbance and neurologic lesion. Brain Lang. 1982; 15: 259–291

    Article  CAS  Google Scholar 

  12. Ohde R, Sharf DJ Phonetic analysis of normal and abnormal speech. University of Michigan, Merrill; 1992.

    Book  Google Scholar 

  13. Turner GS, Tjaden K, Weismer G. The influence of speaking rate on vowel space and speech intelligibility for individuals with amyotrophic lateral sclerosis. J Speech Hear Res. 1995; 38: 1001–1013

    Article  CAS  Google Scholar 

  14. Kotby MN Voice disorders: recent diagnostic advances. Proceedings of Annual Ain-Shams Medical Congress; Cairo, Egypt, March 1–6; 1992

  15. Schulz GM, Grant MK. Effects of speech therapy and pharmacologic and surgical treatments on voice and speech in Parkinson’s disease: a review of the literature. J Commun Dis. 2000; 33: 59–88

    Article  CAS  Google Scholar 

  16. Yunusova Y, Weismer G, Westbury JR, Lindstrom MJ. Articulator movements during vowels in speakers with dysarthria and healthy controls. J Speech Lang Hear Res. 2008; 51: 596–611

    Article  Google Scholar 

  17. Ludlow CL, Connor NP, Bassich CJ. Speech timing in Parkinson’s and Huntington’s disease. Brain Lang. 1987; 32: 195–214

    Article  CAS  Google Scholar 

  18. Freed DB Motor speech disorders: diagnosis & treatment. California State University, Fresno: Cengage Learning; 2000.

    Google Scholar 

  19. Duffy JR, Clinic M Motor speech disorders: substrates, differential diagnosis and management. 2nd ed Saint Louis: Mosby; 2005.

    Google Scholar 

  20. Shohdi S, Khalifa S, Abou Elezz A Assistive diagnostic measures of voice and speech disorders in dysarthric patients. 1995 Cairo University Faculty of Medicine

  21. Jaeger M, Fröhlich M, Hertrich I, Ackermann H, Schönle PW. Dysphonia subsequent to severe traumatic brain injury: comparative perceptual, acoustic and electroglottographic analyses. Folia Phoniatr Logop. 2001; 53: 326–337

    Article  CAS  Google Scholar 

  22. McHenry M. Acoustic characteristics of voice after severe traumatic brain injury. Laryngoscope. 2000; 110: 1157–1161

    Article  CAS  Google Scholar 

  23. Kent RD, Vorperian HK, Duffy JR. Reliability of the multi-dimensional voice program for the analysis of voice samples of subjects with dysarthria. Am J Speech Lang Pathol. 1999; 8: 129–136

    Article  Google Scholar 

  24. Bunton K. Fundamental frequency as a perceptual cue for vowel identification in speakers with Parkinson’s disease. Folia Phoniatr Logop. 2006; 58: 323–339

    Article  Google Scholar 

  25. Weismer G, Yunusova Y, Westbury JR. Interarticulator coordination in dysarthria: an X-ray microbeam study. J Speech Lang Hear Res. 2003; 46: 1247–1261

    Article  Google Scholar 

  26. Kent RD, Kim YJ. Toward an acoustic typology of motor speech disorders. Clin Linguist Phon. 2003; 17: 427–445

    Article  Google Scholar 

  27. Farmer A. Voice onset time production in cerebral palsied speakers. Folia Phoniatr.;32 Basel; 1980. pp. 267–273

    Article  CAS  Google Scholar 

  28. Morris RJ. VOT and dysarthria: a descriptive study. J Commun Dis. 1989; 22: 23–33

    Article  CAS  Google Scholar 

  29. Liu HM, Tseng CH, Tsao FM. Perceptual and acoustic analysis of speech intelligibility in Mandarin-speaking young adults with cerebral palsy. Clin Linguist Phon. 2000; 14: 447–464

    Article  Google Scholar 

  30. Chen H, Stevens KN. An acoustical study of the fricative /s/ in the speech of individuals with dysarthria. J Speech Hear Res. 2001; 44: 1300–1314

    Article  CAS  Google Scholar 

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Correspondence to Dalia Mostafa Osman.

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Refai, M.S., Aziz, A.A., Osman, D.M. et al. Assessing speech intelligibility in a group of Egyptian dysarthric patients. Egypt J Otolaryngol 28, 49–55 (2012).

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