Volume 127, Issue 1, January 2010
Index of content:
- SPEECH PRODUCTION 
127(2010); http://dx.doi.org/10.1121/1.3271276View Description Hide Description
The intra-glottal vortical structures developed in a static divergent glottis with continuous flow entering the glottis are characterized. Laryngeal airflow calculations are performed using the Large Eddy Simulation approach. It has been shown that intra-glottal vortices are formed on the divergent wall of the glottis, immediately downstream of the separation point. Even with non-pulsatile flow entering the glottis, the vortices are intermittently shed, producing unsteady flow at the glottal exit. The vortical structures are characterized by significant negative static pressure relative to the ambient pressure. These vortices increase in size and strength as they are convected downstream by the flow due to the entrained air from the supra-glottal region. The negative static pressures associated with the intra-glottal vortical structures suggest that the closing phase during phonation may be accelerated by such vortices. The intra-glottal negative pressures can affect both vocal fold vibration and voice production.
Acoustic consequences of articulatory variability during productions of /t/ and /k/ and its implications for speech error research127(2010); http://dx.doi.org/10.1121/1.3268600View Description Hide Description
An increasing number of studies has linked certain types of articulatory or acoustic variability with speech errors, but no study has yet examined the relationship between such articulatory variability and acoustics. The present study aims to evaluate the acoustic properties of articulatorily errorful /k/ and /t/ stimuli to determine whether these errors are consistently reflected in the acoustics. The most frequent error observed in the articulatory data is the production of /k/ and /t/ with simultaneous tongue tip and tongue dorsum constrictions. Spectral analysis of these stimuli’s bursts shows that /k/ and /t/ are differently affected by such co-production errors: co-production of tongue tip and tongue dorsum during intended /k/ results in typical /k/ spectra (and hence in tokens robustly classified as /k/), while co-productions during intended /t/ result in spectra with roughly equal prominence at both the mid-frequency (/k/-like) and high-frequency (/t/-like) ranges (and hence in tokens ambiguous between /k/ and /t/). This outcome is not due to an articulatory timing difference, but to tongue dorsum constriction having an overall greater effect on the acoustic than a tongue tip constriction when the two are co-produced.