Changes in linguapalatal contact patterns during therapy for velar fronting in a 10-year-old with Down's syndrome

Articulation errors in the speech of people with Down's syndrome are frequent and often resistant to speech therapy. This preliminary study investigates the use of electropalatography (EPG) to diagnose and treat abnormal articulation patterns associated with velar fronting in a 10-year-old girl.

The study measured changes in the accuracy and stability of linguapalatal (tongue-palate) contact patterns during a 14-week course of visual feedback therapy using EPG. Therapy aimed to resolve a pattern of velar fronting whereby targets /k, g, eta/ had alveolar placement [t, d, n].

The participant was a girl (P) with Down's syndrome aged 10;11 years. P had a moderate-severe speech disorder, which included velar fronting. Her speech was recorded with EPG on three occasions during a 14-week course of therapy: first, before therapy; second, midway through therapy; and third, after therapy. Three analyses were conducted on the EPG data. The first used an EPG classification scheme that identified accuracy of placement for /t/ and /k/ targets. The second was a centre of gravity measure that detected whether P produced a significant difference between /t/ and /k/ targets. The third was a variability index that quantified the stability of contact patterns.

The results of the EPG classification showed that before therapy, /t/ and /k/ targets had identical alveolar placement, reflecting the process of velar fronting. The results after therapy showed that 87% of /k/ targets had accurate velar placement. The centre of gravity measure showed no difference in contact patterns for /t/ and /k/ before therapy, but a statistically significant difference at the second and third recordings. The variability index showed stable contact patterns before therapy for /t/ and /k/ targets, but both became highly unstable midway through therapy, with a return to stability at the third recording. We embed a discussion of P's increased articulation instability during therapy in a recent theoretical framework--dynamic systems--that attempts to account for the emergence of new behavioural forms.

These preliminary results suggest that EPG has potential as an effective diagnostic and therapy procedure for articulation errors in people with Down's syndrome. A major issue still to be addressed, however, is the extent to which others will benefit from this approach to intervention.