NONVERBAL ENVIRONMENTAL SOUND RECOGNITION AFTER UNILATERAL HEMISPHERIC STROKE

Recognition of non-verbal environmental sounds was investigated in 52 subjects with unilateral cerebra-vascular accidents and 18 age-matched normal controls. Impaired performance was most consistently found fol lowing cortical damage of homologous areas in either the left or the r ight hemisphere. Lesions involved the superior temporal gyrus (includi ng the planum temporale), the inferior parietal lobe and the parietal operculum; this area appears to constitute the human auditory cortical processing area. We found different error patterns dependent upon the side of the lesion: patients with right hemisphere damage failed to d iscriminate between acoustically related sounds, patients with left he misphere lesions tended to confuse semantically related sound sources. The impairment following right hemisphere damage was specific for nan -verbal environmental sounds while left hemisphere damage was associat ed with disturbed semantic capabilities in multiple modalities.