Patients who undergo osteotomy experience a radical change in the skeletal relationship between the mandible and maxilla and as yet little is known about how this affects speech articulation. This study investigated the extent to which articulatory placement for the lingual consonant /s/ changed following surgery. Using the technique of electropalatography and acoustic analysis, patients’ productions of fricative sounds were recorded before and after osteotomy. Five patients were investigated, 3 with mandibular prognathism and 2 with maxillary protrusion. Results showed that there were significant changes in articulatory placement after the operation, and that these were correlated with an acoustic measure (CPF). The direction of change could be predicted on the basis of the type of operation undergone, and these changes were maintained 6 months post-operatively. The implications of the findings are discussed.

This case study describes a boy who at the age of eight years did not have consistent or contrastive use of velar stops in his spontaneous speech. The use of electropalatography (EPG) revealed abnormal tongue-palate contact for both velar and alveolar stops, all of which were perceived as normal, there was excess contact in the palatal region for all alveolars and velars in a word initial position and double velar/palatal articulation for velars in a word final position. Therapy using EPG for visual feedback was highly successful and post therapy data showed normal-looking EPG patterns for alveolar and velar stops. The assessment, diagnostic and therapeutic implications are discussed.