Extensions to the International Phonetic Alphabet

The Extensions to the International Phonetic Alphabet for Disordered Speech, commonly abbreviated extIPA , 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.

Source: Wikipedia — Extensions to the International Phonetic Alphabet (CC BY-SA 4.0)