I: Technical Developments Quantitative measures of the palate using enhanced electropalatography

Abstract

SElectropalatography (EPG) is a useful tool for investigating tongue dynamics in experimental phonetic research and speech therapy. However, data provided by EPG are a two-dimensional representation in which all absolute positional information is lost. This paper presents an enhanced EPG (eEPG) system which uses digitised palate shape data to display the tongue-palate contact pattern in three dimenswns. The palate shapes are obtained using a colour-encoded structured light threedimensional digitisation system. The three-dimensional palate shape is displayed on a Silicon Graphics workstation as a surface made up of polygons represented by a quadrilateral mesh. EPG contact patterns are superimposed on to the three-dimensional palate shape by displaying the relevant polygons in a different colour. By using this system, differences in shape between individual palates, apparent on visual inspection of the actual palates, are also apparent in the image on screen. Further, methodr have been devised for computing absolute distances along paths lying on the palate surface. Combining this with calibrated palate shape data allows accurate measurements to be made between contact locations on the palate. These have been validated with manual measurements. In additwn, vocal tract areas in the oral cavity have been estimated by using the absolute measurements on the palate for a given contact pattern, and assuming a jlat tongue profie in the uncontacted area.*Current address: Medical Physics, St Thomas's Hospital, London SE17EH. CHIU, SHADLE AND CARTERElektropalatographie (EPG) bt zwar eine niitzliche Methode zur Untersuchung der Zungendynamik in der Experimentalphonetik und in der Sprachtherapie, aber aufgrund der z wei-dimensionalen Reprasentation von EPG-Daren geht die absolute Positionsinformation verloren. Dieser Beitrag beschreibt ein weiterentwickletes EPG-System, das digitalbierte Daten iiber die Form des Gaumens verwendet, um das Zungen-Gaumen-Kontaktmuster in drei Dimensionen darzustellen. Die Gaumenform wird mit einem 3-0 Digitalbierungs system errechnet, das mit farbkodiertem strukturiertem Licht arbeitet. Die drei dimensionale Gaumenform wird mit einer Silicon Graphics Arbeitsstation als eine aus einem viereckigen Netz bestehenden Polygonflache dargestellt. Die EPG-Kontaktmuster wird durch den Farbkontrast der betroffenen Polygone iiber die dreidimensionale Gaumenform gelegt. Durch den Einsatz diesen Systems, sind die Formunterschiede in den einzelnen Gaumen, die bei der Betrachtung der Gaumen selbst sofort zu erkennnen sin4 auch auf dem Bildschirm erkennbar. Methoden wurden entwickelt, um absolute Entfernungen auf der Gaumenoberflache zu berechnen. In ihrer Verbindung mit der geeichten Gaumenform lassen sie die Kontaktpunkte auf dem Gaumen genau messen. Die Berechnungen wurden manuell bestatigt. Aufierdem wurden Vokaltraktquerschnittsflachen im Mundraum fiir verschiedene Kontaktmaster unter Beriicksichtigung der absoluten Messungen und mit der Annahme eines flachen Zungenprofils aufierhalb der Kontaktregio...

Stroboscopic articulography using fast magnetic resonance imaging

“…vowels (Baer et al 1991) and nasals (Dang et al 1994). MRI techniques displaying dynamic aspects of articulation such as stop consonant production are still a request of research in speech physiology (Narayanan and Alwan 1995) or to supplement with established techniques (Chiu et al 1995).…”

Three-dimensional visualization of electropalatographic data.

“…This procedure made it possible to recover the geometrical relationship between each electrode and landmarks identified by tooth locations on the bottom view of the palate in a 2D field. Saw (1994) and Chiu et al (1995) independently developed similar threedimensional (3D) EPG display systems. In their systems, contact patterns were superimposed on a 3D wire-frame image of the individual artificial palate to describe the geometrical location of constrictions or closures on the artificial palate.…”

Optopalatograph (OPG): a new apparatus for speech production analysis

“…Some work has been carried out to try to extract 3D vocal tract shapes by extending the EPG system. Two similar but independent systems use digitised palate shape data derived from structured light to display the tongue-palate contact pattern in 3D [1] [2]. Some examples are given in which fricative data is processed by generating a composite frame for the entire fricative, and computing an area estimate for each row of the composite frame using the assumption of a flat tongue [1].…”

“…Two similar but independent systems use digitised palate shape data derived from structured light to display the tongue-palate contact pattern in 3D [1] [2]. Some examples are given in which fricative data is processed by generating a composite frame for the entire fricative, and computing an area estimate for each row of the composite frame using the assumption of a flat tongue [1]. In another approach [3] the combination of EPG and EMA complement each other; providing an improved representation of the shape and movement of the tongue which reveals details of tongue kinematics not obtainable from EPG alone.…”