* All vowels make a sound. Vowels are the building blocks of spoken language.
* Words can have silent letters. While a word might begin with a vowel, that vowel might be silent due to the rules of English spelling.
Example:
* The word "hour" begins with the vowel "h", but the "h" is silent.
So, while a word can begin with a vowel and have that vowel be silent, it's not technically a "vowel sound" anymore. It's just a silent letter.