As an aside, what increasingly bugs me is the number of programmers who seem to have bought the urban myth that "An green apple" is grammatically correct, and have proceeded to pepper their project documentation with awkward and incorrect statements.
A comment on the issue[1]:
There is a bizarre urban legend of sorts that you're "supposed to" use "an" if the head noun in the noun phrase it determines begins with a vowel sound, rather than the first word in the noun phrase, giving rise to claims that "an green apple" is somehow "technically" correct. Here is a blog post of someone who seems to have gotten this idea. And here is the discussion on Language Log about that blog post.
In any case, the rule is that you use "an" if the next word begins with a vowel sound. Vowel sound is crucial here because many words that begin with vowel letters do not begin with vowel sounds (e.g. user) and vice versa (e.g. hour).
This makes it a kind of sandhi rule for "intrusive N" in English for indefinite articles, avoiding hiatus between the article and the following word.
As an aside, what increasingly bugs me is the number of programmers who seem to have bought the urban myth that "An green apple" is grammatically correct, and have proceeded to pepper their project documentation with awkward and incorrect statements.
A comment on the issue[1]: There is a bizarre urban legend of sorts that you're "supposed to" use "an" if the head noun in the noun phrase it determines begins with a vowel sound, rather than the first word in the noun phrase, giving rise to claims that "an green apple" is somehow "technically" correct. Here is a blog post of someone who seems to have gotten this idea. And here is the discussion on Language Log about that blog post.
In any case, the rule is that you use "an" if the next word begins with a vowel sound. Vowel sound is crucial here because many words that begin with vowel letters do not begin with vowel sounds (e.g. user) and vice versa (e.g. hour).
This makes it a kind of sandhi rule for "intrusive N" in English for indefinite articles, avoiding hiatus between the article and the following word.
[1] http://english.stackexchange.com/questions/152/when-should-i...