Ninety-six right-handed patients with unilateral hemispheric damage (51 aphasics, 16 non-aphasic left brain-damaged and 29 right brain-damaged patients) and 35 control patients without cerebral lesions were given a sound recognition test requiring the identification of 10 meaningful sounds or noises. The patient was asked to listen to each sound and to indicate which of 4 pictures shown to him represented its natural source. The test allowed both a quantitative score (n° of correct responses) and a qualitative score (n° of acoustic, semantic or odd errors). It was found that while non-aphasic left and right brain-damaged patients performed virtually like normal controls on the test, a significant 348 H. Spinnler and L.A. Vignolo proportion of aphasics (about 25%) fell below the normal cut-off score. The performances of patients with Wernicke's aphasia were particularly poor. In the entire aphasic sample, sound recognition scores appeared to correlate significantly with scores of auditory verbal comprehension (rs = .56). When aphasics were compared to non-aphasic patients with respect to the quality of performance, aphasia was found to be associated more with semantic than with acoustic errors. These findings seem to indicate that the impaired recognition of meaningful sounds, characteristic of aphasics, is due to a great extent to the inability to associate the perceived sound to its correct meaning, rather than to a merely acoustic-discriminative defect. The hypothesis is advanced that this semantic-associative disorder is the common factor underlying both the sound recognition and the auditory language comprehension defects, and that it may manifest itself also in other areas of the aphasic's behavior.