The perception of lexical tone in Mambila

The issue of the perception of lexical tone has been addressed mainly through studies of Southeast Asian languages which feature phonological contour tones as well as level tones. Little attention has been paid to African languages which have, almost exclusively, only level tones. This paper examines tone perception in Mambila, a Benue-Congo language with four level lexical tones. A categorization experiment was run to determine some of the salient aspects of the perceptual nature of these tones. Since the four tones are well defined with respect to production, we sought to determine whether this characteristic carried over into perception, the expectation being that experimental stimuli, on the basis of pitch height alone, would fall into four reasonably well defined categories. Results showed interesting differences across the four tones, with indications that the two Mid tones, T2 and T3, are perceptually different than the High (T1) and Low (T4) tones. The experiment was run a second time, using a group of native English listeners, to assess to what extent results for the Mambila listeners were determined by the perceptual structure of the Mambila tone system. A Signal Detection analysis was used, which revealed important differences between the two groups of listeners. Results are discussed in light of what is known about universal tendencies of tone systems and the historical development of the Mambila system.