A discussion on Facebook not too long ago addressed how to use indefinite articles with abbreviations. Specifically, the question involved the abbreviation “FB” in place of “Facebook.” Should one write “a FB friend” or “an FB friend”?
It depends entirely on whether you would actually say the letters “FB” out loud or if you instantly translate that to “Facebook.” The use of “a” or “an” depends on whether the word that follows begins with a vowel sound or not. Even if you don’t move your lips when you read, you probably still hear the words as they are spoken in your head as you read (unless you are hearing impaired, in which case please accept my apologies.)
To provide an example:
“Don’t worry if the dominatrix breaks the skin. She’s an M.D., after all.”
“Don’t worry if the dominatrix breaks the skin. She’s a medical doctor, after all.”
Things get a bit confusing where the letter “h” is concerned, but the same rule applies. I have long been confused by terms like “an historic event,” because they seem to violate the “vowel sound” rule.
The use of “an” before some “h” words, such as “historic” or “habitual,” is apparently more a British and Canadian thing, arising from accents that do not do much with the “h” sound. If you have an accent that would cause you to say “‘Enry ‘Iggins” instead of “Henry Higgins,” then you would certainly say “an ‘istoric event.” Otherwise, stick to “a historic event.” Do it for the sake of people like me, please.