Normal adult speakers' tongue palate contact patterns for alveolar oral and nasal stops

This study compared tongue palate contact patterns for oral stops (/t/, /d/) with those for the nasal stop /n/ in order to provide normative data for diagnosing and treating individuals with speech disorders. Electropalatographic (EPG) data were recorded from 15 English speaking adults for word initial /t/, /d/ and /n/ in a high and a low vowel context. EPG frames were classified according to three criteria: (1) anterior constriction; (2) bilateral constriction; and (3) zero posterior central contact. Total amount of contact and variability were also measured. The results showed that almost all (99%) stops met Criteria 1 and 3, with fewer articulations (88% of /t/; 83% of /d/ and 55% of /n/) meeting Criterion 2. Although all stops had similar spatial patterns, /t/ and /d/ had more contact and were more likely to have bilateral constriction than /n/. There were no differences in variability between /t/, /d/ and /n/, however. The clinical implications of the results for the management of individuals with speech disorders are discussed.