Ubykh, an extinct Northwest Caucasian language, has the largest consonant inventory of all documented languages that do not use clicks, and also has the most disproportional ratio of phonemic consonants to vowels. It has consonants in at least eight, perhaps nine, basic places of articulation and 29 distinct fricatives, 27 sibilants, and 20 uvulars, more than any other documented language. Some Khoisan languages, such as Taa (or !Xóõ), may have larger consonant inventories due to their extensive use of click consonants, although some analyses view a large proportion of the clicks in these languages as clusters, which would bring them closer into line with the Caucasian languages.

Consonants

Standard Ubykh Phonology

Below is an International Phonetic Alphabet representation of the Standard Ubykh consonant inventory. All but four of the 84 consonants are found in native vocabulary. The plain velars and the voiced labiodental fricative are found mainly in loans and onomatopoeia: ('crow') from Turkish karga), ('slat, batten') from Laz k'avari 'roofing shingle'), ('estate, legacy') from Turkish vakıf), ('the sound of glass breaking'). As well, the pharyngealised labial consonants are almost exclusively noted in words where they are associated with another pharyngealised consonant (for instance, 'handful'), but are occasionally found outside this context (for example, the verb root 'to explode, to burst'). Finally, is mainly found in interjections and loans, with ('now') the only real native word to contain the phoneme. The frequency of consonants in Ubykh is quite variable; the phoneme alone accounts for over 12% of all consonants encountered in connected text, due to the presence of the phoneme in the ergative and oblique singular and plural case suffixes, the third person singular and plural ergative verbal agreement prefix, the adverbial derivative suffix, the present and imperfect tense suffixes, and in suffixes denoting several non-finite verb forms. Very few allophones of consonants are noted, mainly because a small acoustic difference can be phonemic when so many consonants are involved. However, the alveolopalatal labialised fricatives were sometimes realised as alveolar labialised fricatives, and the uvular ejective stop was often pronounced as a glottal stop in the past tense suffix -, due to the influence of the Kabardian and Adyghe languages. The consonant has not been attested word-initially, and is found initially only in the personal name, but every other consonant can begin a word. Restrictions on word-final consonants have not yet been investigated; however, Ubykh has a slight preference for open syllables (CV) over closed ones (VC or CVC). The pharyngealised consonants and have not been noted word-finally, but this is probably a statistical anomaly due to the rarity of these consonants, each being attested only in a handful of words. The alveolar trill is not common in native Ubykh vocabulary, appearing mostly in loan words. However, the phoneme carries a phonaesthetic concept of rolling or a repeated action in a few verbs, notably ~ ('to roll around') and ~ ('to slither').

Karacalar Ubykh Phonology

A divergent dialect of Ubykh spoken by Osman Güngör, an inhabitant of Karacalar in Balıkesir province was investigated by Georges Dumézil in the 1960s. Below is an International Phonetic Alphabet representation of the Karacalar Ubykh consonant inventory. Güngör's speech differed phonologically from Standard Ubykh in a number of ways:

Vowels

Ubykh has very few basic phonemic vowels. The analysis in retains as a separate vowel, but most other linguists do not accept this analysis, preferring one with simpler vertical distinction: and. Other vowels, notably, appear in some loanwords. The question of whether an additional vowel should be retained is of some debate, since it differs from not in length but in quality. However, phonologically and diachronically, it is often derived from two instances of. Even with so few vowels, there are many vowel allophones, affected by the secondary articulation of the consonants that surround them. Eleven basic phonetic vowels appear, mostly derived from the two phonemic vowels adjacent to labialised or palatalised consonants. The phonetic vowels are and. In general, the following rules apply: Other, more complex vowels have been noted as allophones: ('you did it') can become, for instance. On occasion, nasal sonorants (particularly ) may even decay into vowel nasality. For instance, ('young man') has been noted as as well as. The vowel appears initially very frequently, particularly in the function of the definite article. is extremely restricted initially, appearing only in ditransitive verb forms where all three arguments are third person, e.g. ('he gave it to him') (normally ). Even then, itself may be dropped to provide an even shorter form. Both vowels appear without restriction finally, although when is unstressed finally, it tends to be dropped: ('father') becomes the definite form ('the father'). In fact, the alternation between and zero is often not phonemic, and may be dropped root-internally as well: ~ ('hoe'). This kind of allomorphy is called a zero allomorph. argues that there are three vowels which correspond to Dumézil's respectively and this is evident in the minimal triplet of ('I milk X'), ('I reap X'), and ('I milk them; I reap them').