Acoustic Comparison of Vowel Sounds Among Adult Females

When measured acoustic parameters of vowels were compared, results revealed that the vowel sounds had a significant effect on shimmer and VTI. Furthermore, speech sounds classified as back vowels exhibited less perturbation and noise in the acoustic signal: the high-back vowels [u] and []; and the mid-back vowels [o] and [], demonstrated most of the statistically significant reduced values of shimmer and VTI among the 12 vowels compared. Further comparisons among front and back vowels grouped in clusters associated to more and less variability led to statistically significant differences in shimmer, NHR, and VTI. Overall, speech sounds classified as back vowels exhibited less variability and noise. Based on the results of this study, back vowels of the English language should be used in voice acoustic tasks in females, given the higher stability of their acoustic signal, as compared with other vowels tested.