The comments on yesterday’s blog raise several interesting questions (ignoring for the moment those relating to Arabic emphatics).
How does one pronounce a vowel that immediately follows an implosive? Is the airstream for the vowel also ingressive, or does it suddenly change direction to be egressive?
The answer is that in every case — as far as I know — the vowel following an implosive consonant has an unremarkable pulmonic egressive airstream. Note though, that this means that not only does the direction of airflow change, but so in principle does the identity of the initiating cavity. Since voiced implosives (the usual kind) actually involve a combination of airstreams, we can say that in the sequence ɓa there is a constant pulmonic egressive airstream, but that in the first segment it is accompanied by a glottalic ingressive component.
In a vowel-ejective-vowel sequence such as ap̕a the air flow is egressive throughout, but the initiating cavity for the consonant is glottalic — and takes place during a glottal closure, ʔ, that interrupts the egressive pulmonic airstream used for the surrounding vowels.
Clicks have a velaric ingressive airstream, but this is always combined with a velar articulation that interrupts what is normally an egressive pulmonic airstream. So in aǀa (= old aʇa) we have an ordinary pulmonic-air sequence aka with the velaric ingressive operation taking place entirely during the hold phase of the velar plosive.
Ejectives never cluster with implosives. The ingressive pulmonic airstream mechanism appears always to characterize entire utterances rather than individual segments. Reverse clicks are only paralinguistic: they certainly never cluster with ordinary clicks. So we can formulate the universal that we never get an abrupt reversal of the direction of airflow within the same initiating cavity as we pass from one segment to the next in speech.
Glen Gordon asked rhetorically
Ejectives can evolve into implosives or pharyngeals and back again, can't they?The most striking related instance of which I am aware is in the Nguni languages of southern Africa. There we find a regular correspondence between the z of (isi)Zulu and the ejective t̕ of the closely related (si)Swati. We see this in the name of the latter language, which is also known by its Zulu name of Swazi.
The Wikipedia page on Nguni languages gives these example sentences meaning “I love your new sticks”:
|Zulu||Ngi-ya-zi-thanda izi-ntonga z-akho ezin-sha|
|Swati||Ngi-ya-ti-tsandza ti-ntfonga t-akho letin-sha|
So how did this correspondence come about? What kind of consonant could historically have given rise on the one hand to a pulmonic-air voiced fricative and on the other hand to a glottalic-air voiceless plosive? (I can confirm from my own observation that this Swati consonant is indeed ejective.)
It may be relevant that Zulu z is a ‘depressor’ consonant, one of the set that cause the pitch of the following vowel to start lower than it would otherwise do. That perhaps provides a link to the change at the glottis, but the possible pathways of change still seem pretty obscure. Perhaps someone knowledgeable about proto-Nguni can comment.
Or, mutandis mutatis, of some other relevant language family.
(Map taken from here)