Combining Double Vertical Line Below

It marks extra force in how a speech sound is made.

The International Phonetic Alphabet (IPA) is a system for writing speech sounds. Its extended form, extIPA, adds signs for details in speech, including disordered speech. Work on its chart was underway from 1989; publication in 1994 marked official adoption. A Unicode proposal submitted in 1998 says these signs were already used in many publications.

This was a clinical and descriptive tool for linguists and speech pathologists recording how sounds were produced in speech that differs from typical patterns. Here, “strong” means more force in making that sound, not simply greater loudness or stress on its syllable.

Does ͈ always mean strong articulation?

No; other transcription systems reuse it differently.

Unicode’s phonetic chart lists the mark with IPA additions and lists Uralic Phonetic Alphabet additions separately. In extIPA, its documented partner ͉ marks weak articulation. PHOIBLE, a database of language sound systems, uses it for the fortis (stronger) member of a three-way contrast between stronger, plain, and weaker consonants.

A transcription project for Sa’ban, a language, used it for tense consonants, contrasting them with lax consonants. A 2009 Unicode discussion also mentions an A-Hmao notation that contrasts it with the single vertical line below.