Non-verbal environmental sound recognition after unilateral hemispheric stroke

Recognition of non-verbal environmental sounds was investigated in 52 subjects with unilateral cerebro-vascular accidents and 18 age-matched normal controls. Impaired performance was most consistently found following cortical damage of homologous areas in either the left or the right hemisphere. Lesions involved the superior temporal gyrus (including 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 discriminate between acoustically related sounds, patients with left hemisphere lesions tended to confuse semantically related sound sources. The impairment following right hemisphere damage was specific for non-verbal environmental sounds while left hemisphere damage was associated with disturbed semantic capabilities in multiple modalities.