Compensatory articulation in Broca's aphasia.

Thirteen patients clinically diagnosed as Broca's aphasics, were administered a vowel bite block task to ascertain their on-line compensatory articulation ability. Formant frequencies for F1 and F2 were obtained from a pitch-synchronous spectral analysis of digitized vowel waveforms. Bite block/i/productions were consistently characterized by higher F1 and lower F2 frequencies compared to normal vowel productions. Undershooting of tongue elevation and fronting explains this result. No consistent pattern of "off-target" productions were found for/a/tokens. A multiple correlation analysis among clinically derived quantitative measures (BDAE score, oral and verbal apraxia), experimentally derived measures (bite block performance, articulatory reaction time), and neurological measures (brain lesion volume) was highly successful despite a relatively small sample size. Compensatory articulation was significantly related to both oral apraxia scores (r = -.70) and the BDAE total score (r = -.51). A multiple regression analysis nearly reached statistical significance (p = .11) in predicting bite block performance, with oral apraxia the most powerful predictor variable. Descriptive accounts of loci of brain lesion vis-à-vis compensatory articulation ability are given to delimit brain areas thought to possibly mediate this articulatory adaptive skill. Preliminary speculation supports the notion that an intact Area 44 is a prerequisite for successful compensatory ability.