Introduction: Change in resonance is the most commonly experienced speech problems in children diagnosed with cleft lip and palate. The degree of nasality during normal speech production is maintained by the changes in velopharyngeal port. These variations in speech signal are reported to be successfully captured using acoustical tools like spectral analysis.
Aim: The present study investigated to note voice low tone to high tone ratio (VLHR) values for phonation samples of individuals with cleft palate before and after surgery.
Materials and methods: Thirty children with congenital cleft of palate within 8 to 15 years of age participated in the study. Three trials of sustained vowels (/a/,/i/ and /u/) were recorded at their comfortable pitch and loudness level in a noise free room using a hand held dynamic microphone. Praat software that utilized Hillenbrand algorithm was used to extract the VLHR values for samples recorded before and after recovery from the surgery.
Results: Statistical analysis revealed significant decrease in VLHR values after surgery in comparison to before the surgery. Analysis of Variance revealed statistical significant difference at 95% confidence level.
Conclusion: It is concluded that VLHR parameter could be used as an index to measure nasality and can be included in the routine tool assessment protocol.
Keywords: High frequency power; Low frequency power; Perceptual analysis; Vowels.