Comparing the impact of raised vocal effort on various spectral parameters

Vocal effort changes induce various modifications to acoustic characteristics of speech. In this paper we investigate the impact of raised vocal effort on the speech spectrum. In particular, we look at different spectral parameters and compare the changes. The parameters we take into account are spectral tilt, spectral center of gravity, energy ratio and spectral moments. We carry out tests on the complete data set with all phonemes pooled into one distribution and tests with the data divided into three phoneme classes. Furthermore we run vocal effort classification tests to verify our results from statistical analysis. The results indicate significant changes for all parameters on the complete distribution as well as for vowels and sonorants. For obstruents we observe significant changes, too. But the modifications are much smaller than those for the other two phoneme classes. The parameters that are less affected by raised vocal effort are energy ratio and second spec tral moment.