This might be surprising because there are only 5 vowel letters (A, E, I, O, U) in the English alphabet. The reason for this difference is that vowel sounds can be modified in various ways:
* Length: A vowel can be short (like the "a" in "cat") or long (like the "a" in "cake").
* Position of tongue: The position of your tongue in your mouth can change the sound of a vowel.
* Lip rounding: Whether your lips are rounded or spread can also affect the vowel sound.
It's worth noting that some linguists might offer slightly different numbers of vowel sounds, as there is some debate around the exact categorization of certain sounds.