Iconicity and expressiveness of grammatical tones targeting ideophones in Mwaghavul

Abstract All tonally derived verbs in Mwaghavul have ideophonic bases and are derived through one of two lexically determined alternations. In the first alternation, every tone-bearing unit (TBU) of the ideophone surfaces with a mid tone. In the second alternation, every nonfinal TBU of ideophones surfaces with a mid tone, while the final TBU surfaces with a high tone. To express pluractionality, both types of ideophones are reduplicated and follow the second pattern: every TBU of the reduplicant bears a mid tone, and every TBU of the base bears a high tone. While verbs derived through mid-tone overwrite share a tonal melody with underived verbs, only derived verbs have a mid–high melody. Beyond verb formation, the tonal alternations introduce various meanings, conveying the distinguishability of identical elements. We propose that the alternations are triggered by lexically specific allomorphs of a verbaliser, whose exponents are mid and mid–high tonal melodies, respectively. The restriction of the mid–high melody to derived verbs reflects systematicity. For the derived pluractional verbs, the tonal dissimilarity between a reduplicant and its base depicts the distinguishability of otherwise identical elements. We consider the implications of the patterns for linguistic theory, particularly the relationship between grammatical integration and expressiveness.