The role of fundamental frequency and duration in the perception of linguistic stress by individuals with brain damage.

Two tests of the ability of individuals with left-hemisphere damage (LHD) and right-hemisphere damage (RHD) and non-brain-damaged participants to identify phonemic and emphatic stress contrasts were undertaken. From a set of naturally produced base stimuli, two additional stimulus sets were derived. In one, fundamental frequency (F0) cues to stress were neutralized, whereas in the other duration cues were effectively neutralized. Results demonstrated that individuals with LHD were unable to identify phonemic stress contrasts with better-than-chance accuracy; individuals with RHD performed worse than normal participants but significantly better than the patients with LHD--particularly with the original full-cue stimuli. All groups performed better on the emphatic stress subtest, with the scores of only the patients with LHD at chance level for the F0-neutralized stimuli. The findings are considered in relation to hypotheses concerning the hemispheric lateralization of prosodic processing, particularly with respect to a hypothesis that posits differential lateralization for specific acoustic parameters.