Adult speakers' tongue-palate contact patterns for bilabial stops within complex clusters

Previous studies using Electropalatography (EPG) have shown that individuals with speech disorders sometimes produce articulation errors that affect bilabial targets, but currently there is limited normative data available. In this study, EPG and acoustic data were recorded during complex word final /sps/ clusters spoken by 20 normal adults. A total contact (TC) index measured amount of tongue-palate contact during clusters in words such as 'crisps'. Bilabial closure was inferred from the acoustic signal. The TC profiles indicated that normal adults hold their tongues in a steady /s/-like position throughout the cluster; most speakers (85%, n=17) had no significant difference in TC values during bilabial closure compared to flanking fricatives. The results are interpreted as showing that normal speakers produce double bilabial-alveolar articulations for /p/ in these clusters. Although steady state TC profiles were typical of the group, absolute TC values varied considerably between speakers, with some speakers having up to three times more contact than others. These findings add to the knowledge about normal articulation, and will help to improve diagnosis and treatment of individuals with speech disorders.