Obsolete and nonstandard symbols in the International Phonetic Alphabet
The International Phonetic Alphabet 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 for standard. 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 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 to represent the sound of -i in Pinyin hanzi which has been variously described as,, or . 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 for. Extensions from the Americanist affricate convention of c = ts and č = tš include ? = tʂ and ɕ = t?.
While the IPA does not itself have a set of capital letters, 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. Other pseudo-IPA capitals supported by Unicode are .
Capital letters are also used as cover symbols in phonotactic descriptions: = consonant, = vowel, = nasal, = 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 ; extIPA explicitly defines the symbol for this purpose. Both cases 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, nor superscripting for a lesser degree of a feature.
For historical charts including obsolete symbols and values, see History of the International Phonetic Alphabet.