Use Of The A And An Questions Medium
You should use "an" before words starting with a silent "y" when the following word begins with a vowel sound. For example, you would say "an honest person" because the "h" in "honest" is silent and the word "honest" is pronounced with a vowel sound. Similarly, you would say "an hour" because the "h" in "hour" is silent and the word "hour" is pronounced with a vowel sound.