"a" or "an" before an acronym

I found this on another site:

If the acronym is pronounced as a word, such as NASA, then use the article that would be appropriate if it were indeed a word: "a NASA representative."

If the acronym is pronounced as individual letters, such as NSA (National Security Agency), then use the article that would be appropriate when pronouncing the first letter: "an NSA representative."

Just some of the little things you never think about. Normally, "an" always goes before a word beginning with a vowel. Some exceptions to this occur with the use of the letter h, when the accent of the word falls on the second syllable.

an historical event
(today I believe it's technically supposed to be "a" and "a" sounds okay too...but you still here "an" before "an historical event" quite often

an hour

I'd say "an historical event". I'll have nobody tell me I'm technically wrong.

spelling error...."but you still hear"

"An or a before "h"? Rule is, if you pronounce the "h," as in historical, use "a." If the "h" is not pronounced, as in honest or hour, use "an." "

"an" goes before a word beginning with a vowel SOUND.
The *letter* "n" sounds like "e-n" when just speaking the letter.

Yes, if one pronounces the "h" use "a," otherwise use "an."

I was listening to the British parliament, and one of the blokes said, "an historical..." but he aspirated the "h" so it stood out a lot. IT sounded so weird!

Yeah, "an" only sounds okay when one is speaking fast. If you say very slowly...."an historical event" (slow enough so that the h is pronounced) it doesn't sound right. The h is always silent in the word "hour" so it's always "an."

It sounds okay to me.

Which sounds better "an hysterical girl" or "a hysterical girl"?

"an hysterical girl" sounds better if you de-emphasize the "h" in "hysterical". If you pronounce "hysterical" with a hard emphasis on the "h", then "a hysterical girl" sounds better.

I agree with SHW. Usually my "h's" tend to be somewhat hard, so I'd probably use "a hysterical girl."

The problem with the ´historical ´is that, when we have a word beginnig with ´h´ (and that is pronounced) we used ´a´ . But there is a second ruled, not very well mastered, that is: if we have a ´h´ word but if the stress ISN´T on the first syllabus, then it takes ´an´ So: ´AN historical event´ / his-TO-ri-cal/ <-- that´s why! The ´h´ is pronounced but it isn´t the stressed syllable.

People, that is right grammatically speaking. I think if one said ´a historical event´I wouldn´t mind at all.