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.