The Speaker's Formant

The current study concerns speaking voice quality in two groups of professional voice users, teachers (n = 35) and actors (n = 36), representing trained and untrained voices. The voice quality of text reading at two intensity levels was acoustically analyzed. The central concept was the speaker's formant (SPF), related to the perceptual characteristics "better normal voice quality" (BNQ) and "worse normal voice quality" (WNQ). The purpose of the current study was to get closer to the origin of the phenomenon of the SPF, and to discover the differences in spectral and formant characteristics between the two professional groups and the two voice quality groups. The acoustic analyses were long-term average spectrum (LTAS) and spectrographical measurements of formant frequencies. At very high intensities, the spectral slope was rather quandrangular without a clear SPF peak. The trained voices had a higher energy level in the SPF region compared with the untrained, significantly so in loud phonation. The SPF seemed to be related to both sufficiently strong overtones and a glottal setting, allowing for a lowering of F4 and a closeness of F3 and F4. However, the existence of SPF also in LTAS of the WNQ voices implies that more research is warranted concerning the formation of SPF, and concerning the acoustic correlates of the BNQ voices.     

A simplified model of mouth radiation impedance closed by mask cavity

Acoustic radiation impedance of the mouth is an important parameter when the vocal tract is modelled by the equivalent electrical circuit. If the vocal tract is closed by a cavity, as when the speaker wears some kind of mask, total impedance acoustically loading the vocal tract becomes serial connection of the mouth radiation impedance and the mask impedance. In that case the mouth radiation impedance has to be changed compared to free field conditions. This paper introduces a simplified approach to the modelling of that change by an appropriate reduction coefficient. The analysis based on an experiment preformed by measurement in the vocal tract physical model accompanied with analytical estimation has shown that the value of such reduction coefficient is 0.5. The results reveal that for a vocal tract closed with mask cavity the change in mouth radiation impedance introduced in an equivalent electrical circuit can be approximated by the value for free field radiation decreased by about 50%.