Acoustical parameters of Brazilian Portuguese liquids in phonological disorder.

Background: Phonological disorder is one of the most frequent speech and language deficit observed in children and therefore studies using objective evaluation measurements should be developed and implemented during the diagnostic process.

Aim: To describe the acoustic characteristics of /l/ and /r/ liquid sounds.

Method: Speech production samples of 20 children with and without phonological disorder were gathered and acoustically analyzed. Six words were selected for repetition: /se'bola/, /'lama/, [see text]. The analyzed acoustic parameters were F1, F2 and F3, duration and steady-state portion from the target sound and slope analysis.

Results: For words containing /l/, the duration parameter was the great differentiator between the two groups; values of the control group were higher than those found for the group with phonological disorder. Considering words containing /r/ that were correctly produced by the control group and that were always substituted by /l/ in the disordered group, parameters involving duration presented higher values in the disordered group. Slope analysis demonstrated higher values for the control group.

Conclusion: Articulation accuracy of children in the control group was, overall, higher even when considering correctly produced words by the group with phonological disorder containing /l/. The analysis of other acoustic parameters, as well as the application of these parameters to other sounds of the Portuguese language, can help clinicians to make a precise evaluation and, consequently, to improve their therapeutic work.