The role of the frontal and temporal lobes in the phonetic organization of speech stimuli: a multidimensional scaling analysis.

Auditory perception of 10 two-letter consonant-vowel syllables and visual short-term memory for sequences of the same syllables were examined in 28 patients with lesions in the frontal or temporal lobe of either hemisphere and in 12 normal control subjects. Multidimensional scaling analyses showed that manner of articulation and voicing were salient organizational categories for all groups on the auditory task whereas manner of articulation and place of articulation were the salient organizational clusters for all groups on the visual task. The pattern of confusion errors made by all groups on both tasks were consistent with some, but not all, of the phonetic distinctive features expected based on formal linguistic description of human phonology. No group showed a consistent lack of sensitivity across all phonetic features, arguing against the idea that use of a phonetic code is dependent upon any specific focal structure in the cerebral hemispheres.