Analysis of fundamental frequency, jitter, shimmer and vocal intensity in children with phonological disorders

Phonological Disorder is a disturbance of primary manifestation of undefined causes that makes speech become unintelligible. The analysis of vocal parameters becomes important in the process of diagnosis of this disorder, since voice disorders could interfere in the production of speech sounds. Aim: The objective of this study was to verify vocal characteristics related to the intensity and fundamental frequency -F0- and their disturbance indexes - jitter and shimmer - in children with phonological disorders. Study design: clinical prospective with transversal cohort. Material and Method: There were 40 children, 20 of them with phonological disorders and 20 with no speech and language disturbances. Phonological exams with the ABFW infantile language test and spontaneous speech were applied. The Computer Speech Lab was used to record and perform acoustic analyses of the vowels /a/, /e/, /i/, through the vocal parameters: fundamental frequency, intensity, jitter and shimmer. Results: F0 - vowel /e/ was smaller, on average, in the Phonological Disorder Group and it was 126 Hz in the Control Group. To shimmer and jitter there was no evidence that the means of the Phonological Disorder Group were different from the ones of the Control Group (p= 0.191, p= 0.865, respectively). As for intensity, there was evidence that the average did not differ in the Phonological Disorder Group and the Control Group (p= 0.002). Conclusion: The frequency of the vowel /e/ was smaller in the Phonological Disorder Group. There was difference between the two groups regarding the means of intensity of vowels /a/, /e/ and /i/, smaller in the Phonological Disorder Group. No differences between the groups were found regarding the averages of jitter and shimmer.