“Compensatory articulation” in hearing impaired speakers: a cinefluorographic study

Data from three hearing-impaired subjects were compared with data from three hearing subjects to study the effect of constraining the jaw during speech on tongue shape and position for the vowels /i/, /æ/ and /u/. The results showed that although the three hearing-impaired speakers showed more variable tongue shapes and positions in both bite-block and nonbite-block conditions, the bite-block had little effect in altering the areas of maximum constriction between the tongue dorsum and maxilla associated with the vowels studied. Two of the hearing-impaired speakers showed less differentiation in tongue shape and position for the vowels /u/ and /æ/ in both jaw-fixed and jaw-free conditions. A third hearing-impaired speaker differentiated the vowels but the tongue positions observed were different from those of normal hearing speakers. The bite-block was shown to have no systematic effect on intelligibility for any of the hearing-impaired speakers. These findings are interpreted in terms of current thinking on sensorimotor integration and movement control with particular reference to “target-based” theories.