In my last class, a South Korean student told me about his weekend visit to Liverpool. He said it wasn’t easy to understand the local way of speaking, and gave the example of the question word What? He demonstrated how this word had been said, with the final ‘t’ replaced with a silence, or glottal stop, so it sounds like wha’?
The rest of the class agreed that this was indeed a familiar difficulty, though few could express it as clearly as the South Korean student. The problem is that there is a conspiracy of silence surrounding the glottal stop. Since it is not a phoneme of English, it doesn’t appear on phonemic charts, and since it is not on the charts, it is not on the syllabus. Since it is not on the syllabus, it remains under the radar for many teachers and their students. This makes it impossible to talk about. Students in a UK environment are subliminally aware of it, but often can’t put their finger on what it is – it just seems to make the speech of some of the locals sound jagged like broken glass. I don’t know why students should be left to cope with this common feature of English speech with no guidance from teachers. No doubt they can grow accustomed to it on their own, in time and with enough exposure, but the same could be said for many other features of English, such as the schwa, for example. A language class provides an opportunity for focused noticing and accelerated exposure. We should use it. (A glottal stop symbol is included in the PronPack sound chart for this reason)
Ps. The glottal stop is nothing new for many students. For instance, the number eight in Cantonese is transcribed to English as bat, where the ‘t’ represents a glottal stop. There was no better option to transcribe this Cantonese sound (or lack of sound) than the English letter which is so often pronounced that way. Think of Batman for example, and try saying that with a fully pronounced /t/. Pedantic or wha’?
(See also my comments on the glottal stop on hancockmcdonald.com)