Obsolete and nonstandard symbols in the International Phonetic Alphabet

The International Phonetic Alphabet (IPA) possesses a variety of obsolete and nonstandard symbols. Throughout the history of the IPA, characters representing phonetic values have been modified or completely replaced. An example is ⟨ɷ⟩ for standard [ʊ]. Several symbols indicating secondary articulation have been dropped altogether, with the idea that they should be indicated with diacritics. In addition, the rare voiceless implosive series ⟨ƥ ƭ 𝼉 ƈ ƙ ʠ⟩ has been dropped.

Other characters have been added in for specific phonemes which do not possess a specific symbol in the IPA. Those studying modern Chinese phonology have used ⟨ɿ⟩ to represent the sound of -i in Pinyin hanzi which has been variously described as [ɨ], [ɹ̩], [z̩] or [ɯ] (see the sections Vowels and Syllabic consonants of the article Standard Chinese phonology, as well as syllabic fricatives). The term para-IPA is used to describe "symbols that are commonly used within IPA notation but that are not themselves part of the IPA alphabet."

There are also unsupported symbols from local traditions that find their way into publications that otherwise use the standard IPA. This is especially common with Americanist symbols, including affricates such as ⟨ƛ⟩ for [t͡ɬ]. Extensions from the Americanist affricate convention of c = ts and č = tš include 𝼝 = tʂ and ɕ = t𝼞.

While the IPA does not itself have a set of capital letters (the ones that look like capitals are actually small capitals), many languages have adopted symbols from the IPA as part of their orthographies, and in such cases they have invented capital variants of these. This is especially common in Africa. An example is Kabiyé of northern Togo, which has ⟨Ɔ Ɛ Ŋ Ɣ⟩. Other pseudo-IPA capitals supported by Unicode are ⟨Ɓ/Ƃ Ƈ Ɗ/Ƌ Ə/Ǝ Ɠ Ħ Ɯ Ɲ Ɵ Ʃ (capital ʃ) Ʈ Ʊ Ʋ Ʒ⟩ (see case variants of IPA letters).

Capital letters are also used as cover symbols in phonotactic descriptions: ⟨C⟩ = consonant, ⟨V⟩ = vowel, ⟨N⟩ = nasal, ⟨S⟩ = sonorant or sibilant, etc. When these symbols are used for indeterminate sounds, extIPA recommends the use of a surrounding circle ⟨◯⟩. The asterisk ⟨*⟩ is the convention the IPA uses when it has no symbol for a phone or feature, but which is typically determinate (for example the creaky-voiced glottal approximant reported by Ladefoged & Maddieson); extIPA explicitly defines the symbol for this purpose. Both cases (indeterminate sounds and determinate but lacking a formal symbol) may be referred to as wildcard symbols. The table below includes a handful of other nonstandard wildcards.

This list does not include commonplace extensions of the IPA, such as doubling a symbol for a greater degree of a feature ([aːː] extra-long [a], [ˈˈa] extra stress, [kʰʰ] strongly aspirated [k], and [a˞˞] extra-rhotic [a]), nor superscripting for a lesser degree of a feature ([ᵑɡ] slightly prenasalized [ɡ], [ᵗs] slightly affricated [s], and [ᵊ] epenthetic schwa).

For historical charts including obsolete symbols and values, see History of the International Phonetic Alphabet.