Masahiko Wakumoto

Magnetometer observation of articulation in sitting and supine conditions

Magnetic resonance imaging (MRI) has recently emerged as a useful tool for the investigation of the three‐dimensional vocal tract shape in sustainable articulatory targets such as vowels and fricatives. However, existing scanning devices require that subjects phonate in a supine position. Previous work [Whalen, J. Acoust. Soc. Am. Suppl. 1 88 (1990)] compared MRI to cineradiographic data collected in a sitting posture, and reported limited effects of gravity on velar height differences in vowel production. This study used electromagnetometry [Perkell et al., J. Acoust. Soc. Am. 92, 3078–3096 (1992)] to investigate whether detectable systematic differences in midsagittal tongue posture exist between the two phonation conditions. Subjects fitted with nine transducers (four on the tongue, mandible, upper and lower lips, and two for head correction reference) produced both running speech and sustained vowels mimicking MRI protocol, repeated in sitting and supine postures. Analysis of separately recorded acous...

Integration of three‐dimensional and pressure sensitive palatography for speech production study

Tongue‐palate contact patterns during speech production have been measured by electropalatography (EPG). A conventional EPG system produces only a flat contact pattern, and does not provide data for either the three‐dimensional aspect nor tightness of tongue‐palate contact. This paper describes work integrating two recently developed palatography techniques, i.e., three‐dimensional electropalatography (3D‐EPG) [M. Wakumoto and S. Masaki, J. Acoust. Soc. Am. 102, 3166(A) (1997)], and pressure sensitive palatography (PSPG) [M. Wakumoto et al., Proceedings of ICSLP98]. The former displays the electrode pattern on a realistic palatal shape, and the latter measures contact pressure by a thin sheet sensor array. The two systems are combined using the following procedures: (1) individual palatal shape and contact patterns in the 3D field during consonant production are acquired by 3D‐EPG, (2) dynamic tongue‐palatal contact pressure during the same consonant production at the same contact area is monitored by PSP...