Articulatory oral space measures using the modified a-space

The X-ray microbeam method for measurement of articulatory dynamics has been used to acquire large amounts of data, with reduced X-ray dosage, resulting in one of the most widely used freely available speech production databases. The Xray Microbeam Speech Production Database (XRMB-SPD), developed at Wisconsin University, USA, includes a vast amount of coordinate data describing articulatory movements, and acoustic and electroglotographic data collected simultaneously [3]. Honda et al. [2] examined the geometry of the vocal track of American English and Japanese speakers from the XRMB-SPD, using a quadrilateral (A-Space) limited by the palate plane, the anterior nasal spinementon line, the outline of the posterior pharyngeal wall, and a line parallel to the palatal plane, passing through the menton and extending to the pharyngeal wall. In this study the A-Space of different speakers varied in shape. The vowel articulations adapted to the form of the A-Space whilst consonant articulations were independent. The Modified A-Space method was used to select 4 speakers in a study that relates occlusal classes with vowel, fricative and stop production adaptations [1]. It allows the detailed characterization of the XRMB-SPD speakers not just in terms of mid-sagittal-plane area, but also in terms of antero-posterior distance, occlusal plane area, posterior pharynx wall tilt, mandible arch width, and oral cavity volume. This last measure has proven to be far more reliable and has revealed more speaker dependent characteristics than the measure previously proposed in [2].