Meeussen's rule

Meeussen’s rule is a special case of tone reduction in Bantu languages. The tonal alternation it describes is the lowering in some contexts of the last tone of a pattern of two adjacent High tones (HH), resulting in the pattern HL. The phenomenon is named after its first observer, the Belgian Bantu specialist A. E. Meeussen (1912–1978). In phonological terms, the phenomenon can be seen as a special case of the Obligatory Contour Principle.

The term "Meeussen's Rule" (the spelling with a capital R is more common) first appeared in a paper by John Goldsmith in 1981. It is based on an observation made by Meeussen in his 1963 article on the Tonga verb stating that "in a sequence of determinants, only the first is treated as a determinant". It was John Goldsmith who reformulated this as the rule HH > HL (or, as he expressed it, H → L / H     ) which later became well known as Meeussen's Rule.

Meeussen's rule is one of a number of processes in Bantu languages by which a series of consecutive high tones is avoided. These processes result in a less tonal, more accentual character in Bantu tone systems, ending finally in a situation in which there tends to be only one tone per word or morpheme.

Here are some illustrations of the phenomenon in Kirundi (examples adapted from Philippson 1998).

In the first sentence, both the tense marker rá and the verb form báriira (to sew) carry a high tone, signified by the acute accent. They are separated by the pronominal marker zi. In the second sentence, the pronominal marker zi is left out, resulting in two adjacent High tones. Due to the phenomenon described by Meeussen’s rule, the second High tone changes into a Low tone.

These examples show a way of deriving from place names nouns with the meaning ‘a person originating from’. In the first example, the place name bukéeye has a High tone on the second syllable. The junction with umuɲá (‘person from’) has no influence on this tone. In the second example, a place name with a High tone on the first syllable is used. Like above, the second High tone of the resulting pattern of two adjacent High tones is changed into a Low tone due to the phenomenon described by Meeussen’s rule.

Just as HH (High tone + High tone) can become HL (High tone + Low tone) by Meeussen's rule, so also HHH will often become HLL, and HHHH will become HLLL. Thus in the Luganda language of Uganda, the word *bá-lí-lába 'they will see', which theoretically has three High tones, is actually pronounced bálilabá with only one. (The tone on the last syllable is an automatically generated phrasal tone; see Luganda tones.)

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