English gets by on 24 distinct consonants. Taa, also written !Xóõ, has so many that linguists cannot agree on how to count them. Anthony Traill's monumental 1985 study of the East ǃXoon dialect yields at least 58 phonemic consonants on the most conservative reckoning, and the later DoBeS description of West ǃXoon at least 87, but those minima come from treating the most complex clicks as consonant clusters. Count each complex click as a single segment instead and the inventory climbs to around 130 consonants on Traill's material and 122 on DoBeS's — the figure WALS cites when it ranks Taa's inventory the largest of any documented language. On every one of these counts, Taa holds the record.
Taa is a Tuu language (formerly grouped with the now-discredited "Southern Khoisan" family) spoken in scattered villages of the southwestern Kalahari, mostly in Botswana with a smaller community in Namibia. Estimates put the speaker community at around 2,500 people, all of whom are bilingual in Tswana, Afrikaans or Khoekhoegowab, so although the language is not yet moribund, every generational hand-off is a coin flip.
The phonological extravagance has three layers:
- Five primary click types. Dental |, lateral ||, alveolar !, palatal ǂ and bilabial ʘ. Bilabial clicks — made with a kiss-like pop — survive in only a handful of languages worldwide; Taa is one of them.
- Roughly 17 click accompaniments. Each click can be voiced, voiceless, aspirated, glottalised, nasalised, prenasalised, breathy-voiced or combined with uvular and ejective releases. Multiply 5 × 17 and the click inventory alone outnumbers the entire consonant system of Hawaiian several times over.
- A separate non-click consonant series almost as large as a normal language's whole inventory, with rare contrasts like uvular ejective affricates q'χ.
The South African linguist Anthony Traill spent more than thirty years documenting Taa, beginning with PhD fieldwork in the 1970s and culminating in his 1994 dictionary, A !Xóõ Dictionary. Traill's instrumental work — using static palatography, aerodynamic measurement and X-ray imaging — showed that what early visitors had dismissed as "accidental noises" were in fact fully voluntary articulations with distinct closures at the velum and the epiglottis. He demonstrated that a single Taa click can recruit all three of the airstream mechanisms available to human speech: the ingressive lingual airstream of the click itself, an egressive pulmonic airstream for the voicing that leads into it, and a glottalic one for the ejective release that follows — while a further series lowers the velum to add nasalisation.
Traill's point was not rhetorical but statistical. Taa clicks are not a marginal or decorative corner of the inventory: they are ordinary consonants of the language, and they are in fact the preferred way to begin a word — by one count 82% of basic vocabulary items start with a click, a far higher rate than for any non-click series.
Linguists disagree about why Taa got so loud. One long-popular hypothesis — argued most visibly from the genetics side by Alec Knight, Peter Underhill and colleagues in 2003 — is that the Kalahari has been a refuge zone since at least the late Pleistocene, and that the phonological extravagance is an extremely old accumulation, possibly mirroring the soundscape of much earlier hunter-gatherer languages now lost. Specialists on the languages themselves are far more sceptical: Bonny Sands and Tom Güldemann have argued that clicks are not relics of an ancestral mother tongue, that there is no special linguistic conservatism to be found in the region, and that the spread of clicks belongs to the relatively recent human past rather than to the dawn of language. Whichever way that argument settles, Taa offers a sobering counter to the idea that human languages "tend toward economy": when geography and demography allow it, phonology can spiral upward almost indefinitely.
Taa is generally described as severely endangered. The few hundred children who still acquire it grow up alongside Tswana-medium schooling and increasingly mobile lifestyles. A break in transmission would end the daily use of the language and remove an important source of evidence for how complex a consonant inventory can become.