Long-Term Average Spectrum as an Outcome Measure of Vocal Projection After Resonant Voice Therapy in Carnatic...

The current study evaluated the effects of resonant voice therapy (RVT) on the long-term average spectrum (LTAS) parameters of vocally healthy trained Carnatic classical singers. The objectives of the study were i) to understand the perceptual differences and ii) to understand the change in LTAS contour parameters and the alpha ratio of the sung voice samples of the trained Carnatic classical singers before and after RVT.

The study used a quasi-experimental, pre post design and purposive-convenient sampling method. Nineteen vocally healthy singers (4 males and 15 females) aged 18-25 years (M = 23; standard deviation [SD] = 2.09) with minimum 10 years of formal Carnatic classical vocal music training volunteered to participate in the study. The audio recordings of the participants' sung aakaara (/a/ vowel singing) were obtained before and after the training. All participants were assigned to a 21-day-long RVT training program scheduled as 15-20 minutes sessions. The participants' pre-training and post-training singing samples were subjected to LTAS analysis. The spectral mean, SD, skewness, kurtosis, and alpha ratio were extracted from the sung samples. The mean and SD of the parameters were obtained using descriptive statistical methods. Wilcoxon signed-rank test was performed to evaluate significant differences in the obtained parameters across pre-training and post-training sung samples.

Though there was an increase in perceptual vocal resonance in the post-training sung samples, the difference was observed to be statistically insignificant. The results indicated a significant difference only in the alpha ratio values, which were decreased, indicating an increase in the high-frequency energies. The descriptive statistical evaluations showed a reduction in the parameters of spectral mean, SD, skewness, and kurtosis.

The observations from the current study indicated that the RVT training increased the energies of higher frequencies in the singers' voices (1-5 kHz). This high-frequency energy favored improved voice projection, imparting perceptual resonance or ringing quality of the voice.