Linguistic and extralinguistic variables for the complexity of tonal systems: the case of African languages

This study shows that the complexity generated by the existence of distinctive tones in a language can be defined differently according to the approach chosen. Aiming to go beyond the relative and absolute approaches, without excluding some of their assumptions, the complex systems approach emphasizes the impossibility of defining complexity by reference to a single central parameter, difficulty and cardinality, respectively. This paper intends to identify those properties of language tonologies that make them complex systems. In particular, it stresses the close interweaving of the tonal system with systems of different size and the impossibility of isolating it not only from the phonological system, but also from the non-linguistic environment without consequences and information loss. The principle of nested systems allows to focus on the issue of how and to what extent factors like number of consonants and vowel qualities, syllable size, genes, climate and language acquisition influence the structure of tonal systems, and on the possible explanations for several large-scale typological correlations between these parameters. The analysis advocated here regards tones as emergent structures that result from the self-organization capacities of the phonological system in response to the interaction of segmental, suprasegmental and non-linguistic factors, but also as features causing the emergence of processes conditioned both segmentally and suprasegmentally.