Extensions to the International Phonetic Alphabet

The Extensions to the International Phonetic Alphabet for Disordered Speech, commonly abbreviated extIPA /ɛkˈstaɪpə/, are a set of letters and diacritics devised by the 1989 Kiel Convention and later by the International Clinical Phonetics and Linguistics Association (ICPLA) to augment the International Phonetic Alphabet for the phonetic transcription of disordered speech. Some of its symbols are also used to represent features of normal speech in IPA transcriptions, and are accepted for that purpose by the International Phonetic Association.

Many sounds found only in disordered speech are indicated with diacritics, though an increasing number of dedicated letters are used as well. Special letters are included to transcribe the speech of people with lisps and cleft palates. The extIPA repeats several traditional IPA diacritics that the ICPLA has found are unfamiliar to most speech pathologists but which transcribe features that are common in disordered speech. These include preaspiration ⟨ʰ◌⟩, linguolabials ⟨◌̼⟩, laminal fricatives [s̻, z̻], and ⟨*⟩ for a sound (segment or feature) that has no available symbol (letter or diacritic). The novel transcription ⟨ɹ̈⟩ is used for an English molar-r, as opposed to ⟨ɹ̺⟩ for an apical r; these articulations are acoustically indistinguishable and so are rarely identified in non-disordered speech.

Sounds restricted to disordered speech include velopharyngeals, nasal fricatives (a.k.a. nareal fricatives) and some of the percussive consonants. Sounds sometimes found in the world's languages that do not have symbols in the basic IPA include denasals, the sublaminal percussive, palatal and velar lateral fricatives, and fricatives that are simultaneously lateral and sibilant.

There are two basic approaches to transcription in extIPA. One is to transcribe speech phonetically, without considering what the intended sounds are. For example, if a target sound /m/ is denasalized to [b], it is written ⟨b⟩. The other approach is to transcribe the target sound with diacritics to indicate how it is mispronounced. With this approach, denasalized /m/ is written ⟨m͊⟩, with the denasalization diacritic ⟨◌͊⟩. This semi-phonemic approach is very common in the literature, but the ICPLA tries to discourage it. For this reason, in 2025 they specified the denasalization diacritic as meaning partially denasalized.

The extIPA was substantially revised and expanded in 2015; the new symbols were added to Unicode in 2021. Two diacritics were changed in 2024 to reduce ambiguity. (See History of the International Phonetic Alphabet § ExtIPA.)