Articulatory coordination and the clinical profile of two cleft palate speakers

Articulatory movements of two post surgical cleft palate patients were studied using cinefluorographic procedures (24 frames per second). The subjects both achieved closure during a sustained production of /u/ but had different clinical profiles. The coordination of the velum with other articulators (jaw, tongue dorsum and tongue tip) and with voicing was analysed in order to demonstrate the hypothesized relationship between articulatory timing and nasality. The results show that the movement of velum differed dramatically between these two subjects. For S2, the subject with the higher nasality ratings, velar closure was achieved less consistently than for S1. When it was achieved it often came after voice onset or after the maximum vocal tract constriction had occurred. These relationships, it is argued, are conducive to increases in nasal resonance. The data suggest that many of the timing patterns shown may be accounted for by the mechanical constraints placed on the velum by the lowering of the jaw and tongue. It is suggested that in order to determine precise role of neuromuscular and mechanical parameters in velar function or dysfunction, comprehensive modelling of velar activity needs to be pursued.