Case variants of IPA letters

With the adoption of letters from the International Phonetic Alphabet (IPA) in various national alphabets, letter case forms have been developed. This usually means capital (upper-case) forms were developed, but in the case of the glottal stop ʔ, both upper-case ⟨Ɂ⟩ and lower-case ⟨ɂ⟩ are used.

The adoption of IPA letters has been particularly notable in Sub-Saharan Africa, in languages such as Hausa, Fula, Akan, Gbe languages, Manding languages, and Lingala. The most common are open o ⟨Ɔ ɔ⟩, open e ⟨Ɛ ɛ⟩, and eng ⟨Ŋ ŋ⟩, but several others are found. Kabiyé of northern Togo, for example, has ⟨Ɔ ɔ, Ɛ ɛ, Ɖ ɖ, Ŋ ŋ, Ɣ ɣ, Ʃ ʃ, Ʊ ʊ⟩ (or ⟨Ʋ ʋ⟩), as in this newspaper headline:

Some of the IPA letters that were adopted into language orthographies have since become obsolete in the IPA itself. And although one might think that the click letters ⟨ʘ ǀ ǃ ǂ ǁ⟩ were adopted from the IPA without case, the reverse happened: they were adopted into the IPA from Nama, replacing the dedicated IPA letters ⟨ʇ ʗ ʖ⟩; Nama never did have case for these letters.

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