Dipping and Falling as competing strategies for maintaining the distinctiveness of the low tone in the four-tone system of Kaifeng Mandarin

Kaifeng Mandarin has four tones (LH, HL, H, L), among which the citation pronunciation of L is an f0 fall (the ‘Falling variant’) for some speakers and a falling-rising f0 contour (the ‘Dipping variant’) for others. Seeking to comprehend the rationale behind this idiosyncratic variation, we decided to investigate the distinctiveness of each variant of L with each of the three other tones, LH, HL and H. Accordingly, we constructed six ten-step f0 continua, using two naturally spoken syllables [ma] spoken by a male and a female speaker as source files. In a two-alternative forced choice task, the Falling and Dipping variants turned out to be equally distinctive. Specifically, the results revealed distinct categorizations between the Dipping variant and HL as well as between the Falling variant and LH. However, when the Dipping variant needed to be distinguished from LH and the Falling variant from HL, recognition accuracy dropped significantly, favoring the complex tone. The two L-variants were equally discriminable from H. This overall functional similarity of the two variants goes some way towards understanding their coexistence within the same speech community. Because communicative intentions played no role in the experiment, it remains to be seen if the distribution across speakers will remain stable in production experiments that vary communicative duress, as created by the need to discriminate between the L-tone and each of the two complex tones.