Cori language

The Cori (Chori) language is a minor Plateau language spoken in a single village in Kaduna State in Nigeria.

Cori is known for having six distinct levels of tone, too many to transcribe using the International Phonetic Alphabet, which allows five. However, there are only three underlying tones: 1 (top), 4 (mid), and 6 (bottom), which are all that need to be written for literacy. Most cases of Tone 2 (high) are a result of tone sandhi, with 4 becoming 2 before 1. Tones 3 (mid-high) and 5 (low) can be analyzed as contour tones, with underlying /1͡6/ realized as [3] and /2͡6/ realized as [5].

In order to transcribe the surface tones without numerals (which are ambiguous), an extra diacritic is needed, as is common for four-level languages in Central America: