no (audible) release

Plosives are traditionally analysed phonetically as having three stages or phases:
(i) the “approach” phase, during which the primary articulators move into contact;
(ii) the “hold” (or “compression”) phase, during which the contact is maintained, blocking the escape of the air stream, so that air pressure builds up behind the closure; and
(iii) the “release” phase, during which the primary articulators move apart, allowing the compressed air to escape explosively.

In the case of “nasal release” (as in the d of hardness) it is not the primary articulators that move apart, but the soft palate that moves away from the rear wall of the pharynx, allowing the compressed air to escape nasally; in the case of “lateral release” (sadly) it is the side rims of the tongue (or more generally the side part of the primary articulators) that move, allowing the compressed air to escape laterally. Logically, we can also speak of “nasal approach” and “lateral approach” for the variants of stage (i) in which it is not the primary articulators that move into contact, but the soft palate or side part of the articulator respectively.

In the case of “geminated” plosives, as in Italian fatto, the hold phase of the plosive lasts for an extra long time. If you prefer to describe this event as consisting of two entities, corresponding to each of the phonemes involved (here, /tt/), you can say that the first has no release and the second has no approach. In that sense you can also say that in the English phrase good dog the first d has no release, the second d no approach. But at the physical level we really have just a single plosive with the same three phases as any other plosive, the hold phase simply lasting longer than usual.

In the usual English pronunciation in cases such as actor ˈæktə, logged on ˌlɒɡd ˈɒn, the two adjacent plosive articulations (here, velar and alveolar respectively) overlap in time. This means that the release of the first plosive is “masked” by the second. The auditory signal shows us a velar approach, then a long hold, then an alveolar release. The first plosive is sometimes labelled “unreleased”, though a better term would be to say that it has “no audible release”. (The second plosive could also be called “unapproached”, or better “with no audible approach”, but people don’t often mention that.)

The IPA provides a special diacritic, [˺], U+031A, meaning “no audible release” (Handbook of the IPA, p. 182, 204, and the IPA Chart). We could write this pronunciation narrowly as ˈæk˺tə, ˌlɒɡ˺d ˈɒn. (Unfortunately, U+031A doesn’t display properly, so in its place I’ve used U+02FA, which looks the same.)

The Unicode Standard, unfortunately, glosses U+031A as “IPA: unreleased stop”. And it is true that Cantonese final stops, English k in actor, etc are sometimes termed “unreleased”. I think this terminology is inappropriate.

Daniel Jones used to speak of “incomplete plosive consonants” and to say that such consonants “have no plosion”. What he meant was that they have no audible plosion. We no longer use his terminology, saying nowadays that they have no audible release.

Burmese, Cantonese, and Thai are examples of languages in which syllable-final plosives regularly have no audible release. This applies not only utterance-finally but also utterance-medially no matter how the following syllable begins. The explanation is usually a supervening (overlapping, masking) glottal closure, giving [t˺ʔ] etc. But — utterance-finally, at least — it could theoretically also be because the lungs relax and so stop creating an airstream.

Magda Zając, a PhD student at the University of Łódź, wrote to me about “unreleased” stops.

Do you think an unreleased stop can sometimes appear in intervocalic contexts? E.g. in phrases like: that itchy goose, that area was, she measured out a lot.

Clearly, the ts in these phrases can sometimes be pronounced as glottal stops, ʔ. But they can also be pronounced in a way that involves an alveolar articulation with complete closure, yet without the noise burst associated with alveolar release.

One of Magda’s teachers had told her that some of the sounds that she took to be glottal stops were “actually unreleased /t/s”. But another of her teachers had told her that he didn't think it was possible to have an unreleased stop intervocalically. So who was right?

I think they were probably t with no audible release. An overlapping glottal plosive masked the alveolar release.

I said

Physiologically, you can't have a fully “unreleased” plosive between vowels. In any plosive there is a compression stage, during which the air stream gets compressed behind the closure. Either this compressed air is ultimately released (by the removal of the oral closure, or alternatively by the removal of the velic closure as the soft palate moves) — or the initiator of the airstream (the lungs, usually) ceases to provide the pressure.

In utterance-final position you might have a truly unreleased plosive, with the lungs ceasing to maintain the air pressure. But not in mid utterance!

If it sounds like an unreleased plosive, perhaps it is really an oral
plosive with a supervening glottal closure. After the oral closure is
complete the glottis closes, thereby holding the air pressure from the
lungs. When the oral closure is released, the closure is inaudible because there is no air pressure behind it.

So I would call it "no audible release", not absence of release.

Magda is not satisfied.

Yes but what I don't quite understand is the following: What, exactly, is the difference between a word-final plosive with inaudible release and a word-final unreleased plosive? Because if I understand correctly, in both cases the air compression becomes weak and no relase stage can be heard. So can these terms be used interchangeably with regard to word-final plosives?
I'm really sorry for the pestering, but I really can't get my head around the difference between "unreleased" and "no audible release", especially since at times it seems that both terms are used to refer to the same phenomenon (e.g. in Gimson's pronunciation of English in the section about the release stage of English plosives).

I don’t know what further I can say to make my view clearer. It is true that in the Gimson book (seventh edition, 2008, ed. Cruttenden) the term “unreleased” does make one, isolated, appearance. Let’s put this down to an uncharacteristic lapse on Cruttenden’s part.

Let’s boycott the term “unreleased”.