When should I use "a" versus "an" in front of a word beginning with the letter h?

A basic grammar rule is to use an instead of a before a vowel sound. Given that historic is not pronounced with a silent h, I use “a historic”. Is this correct? What about heroic? Should be “It was a heroic act” or “It was an heroic act”?

I remember reading somewhere that the h is sometimes silent, in which case it’s an, and when the h is pronounced, it’s a. But then I also remember reading that it depends on which syllable is stressed. And I also think I read somewhere that it might differ between British and American English.

Personally, I pronounce the h, and believe that a is correct. I find that it sounds incorrect to use an and pronounce heroic without the h.

So how do I know when to use a and when to use an with a word beginning with the letter h? Are both acceptable or is there one that is correct?

Indeed, you are correct.

In certain accents, history, hotel, etc. are pronounced with an h sound. In those accents, a should be used. In other accents, such as my own, it is pronounced without an h sound, and therefore starts with a vowel. In that accent, it would be correct for one to say an.

Queen Elizabeth II is one such person who could correctly say an historic event. President Obama is one such person who could correctly say a historic event.

In writing, it doesn't really matter which one is used.

The point of the word an is to avoid the awkward silent pause between words when saying something like "a apple." So, you should put an before any word that begins with a vowel sound, not just a vowel letter.

The good news is that you just need to do whatever makes sense when talking:

• a historian
• an honor
• a xylophone
• an X-ray
• a user (begins with y sound)
• an umbrella
• a one-eyed pirate (begins with w sound)
• an owl

It is a traditional rule of English that an can be used before words that begin with an H sound if the first syllable of that word is not stressed. Indeed, some traditionalists would say it must be used before such words. Since the first syllable of historic is unstressed, it is acceptable to use an before it.

In the Corpus of Contemporary American English, there are 1591 incidences of “a historic” and 428 incidences of “an historic”, showing that usage of an before such words is dying out.

Holy Moly (Or Oly Moly):

Google books ngram viewer for "a historic" and "an historic"

In words beginning with “h” where the accent is on the 2nd syllable, it is also correct to use "an". In such cases you do not pronounce the “h”.

So "an historical act" is spoken as "an'istorical act".

This practice has a long, respected pedigree, at least in British literature.