In Universities^x, Vowels^x

For the usage of "a" or "an", what really matters is the first SOUND of the following noun. We say: a car, a pen, a man. The sounds following "a" are consonant sounds. So: an elephant, an animal, an umbrella. In this case, the initial sounds after "an" are vowel sounds. We say an umbrella,...

As far as I know 'a unique' is correct because in that case 'u' is not a vowel but a semi-consonant (or semi-vowel) like in university, unify, uniform, utopia and many with the sound -/ju/ at the beggining of the word.

I would say we use "a/an" before a "semi-consonant vowel sound "-for instance: a University, an hour.

As a general rule: AN is used when the next word begins with a vowel......an Apple. A is used when the next word begins with a vowel.........a Book. BUT..... We use AN before a vowel sound, even if it is written with a consonant... e.g. An hour, an honour, We use A before a consonant sound, even...