I received an email from a listener of my podcast Ron’s Amazing Stories. He was criticizing my use of “an” verses “a”. I have always thought the usage was based on whether the next word in the sentence began with a vowel or a consonant. As it turns out it is a bit more complicated. Let’s look at an example:
John waited on the corner for an hour. While he waited a historic event occurred.
You will notice that, “an hour” works. Why is that? Well, it is because hour starts with a vowel sound. In the case of historic it uses the h sound and therefore uses an “a”. Yes, I am quite aware how crazy that sounds. Here is another example:
John was thinking about how he wants to work as a missionary. However, before he will do that he wants to get an MBA.
The letters o and m can be tough to determine usage for. The reason is the “o” can be used as a “w” like in the word “onetime”. So, the bottom line to this is simple. The rule whether to use “a” or “an” is actually determined by how the word is pronounced not the letter used.