Sotho Tonology - Tonal Rules - Typology

Typology

One popular classification of tonal Bantu languages broadly separates them into two group: shifting languages and spreading languages. The Sotho–Tswana languages are bounded spreading languages as they have primitive rules which directly cause underlying high tones to be associated with (spread to) syllables to the right. The closely related Nguni languages, on the other hand, are unbounded shifting languages as they have primitive rules which directly cause underlying high tones to be moved (shifted to) syllables to the right. The following table presents an informal comparison between the tonal processes found in Sesotho and isiZulu (█ = isiZulu, █ = Sesotho):

In the table, a process is unbounded if there is no set limit on the number of syllables over which it may occur. Sesotho has basic bounded spread (High Tone Doubling) and isiZulu has basic unbounded shift. Bounded shift in Sesotho occurs as the cumulative effect of bounded right tone spread (High Tone Doubling) and Left Branch Delinking, while various forms of spreading may occur in isiZulu if the word is very short or has two or more underlying highs.