AN ARTICULATORY STUDY OF FRICATIVE CONSONANTS USING MAGNETIC-RESONANCE-IMAGING

Magnetic resonance images of the vocal tract during sustained producti on of the fricatives /s, integral, f, theta, z, 3 v, 0/ by four subjec ts are analyzed. Measurements of vocal-tract lengths and area function s, and morphological analyses of the vocal tract and tongue shapes for these sounds are presented. Interspeaker differences in area function s are found to be greater in the pharyngeal cavity than in the buccal cavity with the nonstrident fricatives exhibiting greater differences than the strident ones. The anterior tongue body of the alveolar strid ents exhibit concave cross-sectional shapes while that of the postalve olars show a relatively raised tongue body with flat or slightly conve x cross-sectional shapes. The concave tongue shapes of the alveolars r esult in a more abrupt area function behind the constriction when comp ared to that of the postalveolars. Laminality or apicality of articula tion is found to be speaker dependent. Moreover, a greater degree of a nterior medial grooving and lateral lingua-palatal contact is found in apical alveolar fricatives than in laminal ones. The posterior tongue body of all fricatives shows concave cross-sectional shapes. Voiced f ricatives are characterized by larger pharyngeal volumes than the unvo iced fricatives due to tongue-root advancement. Tongue-shape asymmetri es are found to be subject and, in some cases, sound dependent. (C) 19 95 Acoustical Society of America.