Three-dimensional tongue surfaces from ultrasound images

摘要

This paper presents 3D tongue surfaces reconstructed from sixty cross-sectional slices of the tongue. Surfaces were reconstructed for sustained vocalizations of 18 American English sounds. Electropalatography (EPG) data also were collected for the sounds to compare tongue surface shape with tongue-palate contact patterns. The ultrasound data were grouped into four tongue shape categories. These classes were front raising, complete channel, back raising, two-point displacement. The first three categories contained both vowels and consonants, the last only consonants. The EPG data indicated three categories of tongue-palate contact: bilateral, cross-sectional, combination of the two. Vowels used only the first pattern, consonants used all three. The EPG data provided an observably distinction in contact pattern between consonants and vowels. The ultrasound tongue surface data did not. The conclusion was that the tongue actually has a limited repertoire of shapes, and positions them against the palate in different ways for consonants vs. vowels to create narrow channels, divert airflow and produce sound.