grammar: the use of "an"

18:38 Jan 31, 2020 

I think the h thing might have to do with whether the word is germanic or latin/romance in origin though. As for the u, when a word starts with the letter u, and if this letter is pronounced /ju/, which is a consonant sound, as Lincoln pointed out, then the article will be a. If the letter u is pronounced /ʌn/ however, then the article is an. Example: an unruly child.

08:41 Jan 29, 2020 

Excellent discussion; hope not only me, but others benefit from it.

08:28 Jan 29, 2020 

It is nothing to do with what it modifies — it is entirely about the euphony of how the 'u' is pronounced in EN. Almost no-one would ever claim that 'university' should be pronounced 'ooniversity'; but there are a few specific words where older / pedantic users may cling to a dated convention of using 'an', in e.g. 'an unique experience'
I think you can tell your customer that they are being very old-fashioned if they attempt to follow that practice!

Note that a similar thing happens with certain words beginning with 'h' — and in this case, the practice very definitely survives today, as some 'h's are pronounced and some are not: it sounds natural to say 'a hospital' or 'a host' — but equally, to say 'an hour'; there is less certainty about e.g. 'an hotel' (which some people tend to consider rather affected these days) or 'an historic moment'.