Hemispheric differences in the perception of Zulu click consonants

Past research has shown that speech sounds are processed better by the left hemisphere, nonspeech sounds by the right hemisphere, in most right-handed people. To date, however, it is unknown whether phonetic contrasts from an unfamiliar language show this same pattern, and whether they are perceived as speech. It is known that adults’ perception of non-native speech contrasts is strongly influenced by their language experience; thus non-native contrasts may be handled by different processes than are native contrasts. Best etal. [JEP:HPP 14, 345–360 (1988)] suggested that English speakers’ excellent discrimination of Zulu click consonants occurs because they hear the clicks as nonspeech. Right-handed native speakers of English and of Zulu or Xhosa participated in a dichotic listening study on cerebral dominance for perception of clicks in isolation and in /Ca/ syllables. Natural tokens of Zulu click consonants were used (apical, lateral, and palatal places of articulation, and voiceless aspirated, voiceless unaspirated, and voiced categories). Native speakers of Zulu and Xhosa showed a left hemisphere dominance for discrimination of both the isolated clicks and /Ca/ syllables, while native speakers of English demonstrated no such hemispheric dominance. [Work supported by NIH Grant No. HD-01994.]