Floating tone

An example occurs in Bambara. Bambara has two phonemic tones, high and low. In this language, the definite article is a floating low tone. With a noun in isolation, it docks to the preceding vowel, turning a high tone into a falling tone: [bá] river; [bâ] the river. When it occurs between two high tone, it downsteps the following tone:

• it's not a river
• (or ) it's not the river

Also common are floating tones associated with a segmental morpheme such as an affix. For example, in Okphela, a Niger-Congo language of Nigeria, the main negative morpheme is distinguished from the present tense morpheme by tone; the present tense morpheme (á-) carries high tone, whereas the negative past morpheme (´a-) imposes a high tone on the syllable which precedes it:

• oh á-nga he is climbing
• óh a-nga he didn't climb

Floating tones derive historically from morphemes which assimilate to the point where only their tone remains.