Evidence of the significance of secondary excitations of the vocal tract for vocal intensity.
In the production of voiced speech the main excitation of the vocal tract occurs during the glottal closing phase when the rate of change of the flow reaches its absolute maximum. The level of this maximum, the negative peak amplitude of the differentiated glottal flow, correlates strongly with sound pressure level. This study presents a straightforward method that yields a numerical value to characterize the effect of the main excitation on vocal intensity. The method, energy ratio by modified excitation (ERME), utilizes the glottal flow and the vocal tract transfer function estimated by inverse filtering and it synthesizes two signals based on the linear source-filter theory. The first sound is produced using the glottal flow given by inverse filtering per se. The second signal is synthesized by removing the main excitation from the differentiated flow. ERME is defined as the ratio between the energy of the first synthesized signal and the energy of the second one. It is shown that when the loudness of speech increases, the value of ERME first rises but in the case of very loud voices it starts to decrease. Hence, ERME shows that effects of secondary excitations of the vocal tract that occur during glottal opening become important in the production of very loud voices.
Alku
P
P
Acoustics Laboratory, Helsinki University of Technology, Finland. Paavo.Alku@hut.fi
Vintturi
J
J
Vilkman
E
E
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010699:Phonation / Q000502:physiology*; D013068:Speech Production Measurement; D014831:Voice / Q000502:physiology*; D014833:Voice Quality