by RonPurewal Tue Jun 10, 2008 6:30 am
you use 'an' before vowel sounds, not necessarily before vowels.
usually the correlation is close to perfect - words starting with vowels always start with vowel sounds, and words starting with consonants almost always start with consonant sounds - which is why you have probably never considered this issue before.
go ahead and say 'a MBA' out loud (note that 'MBA' starts with a vowel).
unless you have a new england accent, in which the awkward gap between 'a' and 'm' might be filled in with an intrusive 'r'-type sound, this will be difficult to pronounce.
same goes not only for acronyms, but for normal words that begin with consonants but nevertheless begin with vowel sounds:
an herb (not 'a herb')
an honor (not 'a honor')
etc.