Question

how many vowel sounds are there?

Answer 1

There are 5 Vowels:-
a    e    i    o    u 

Answer 2

THIS IS THE ANSWER FOR UR QUERY:
Some texts speak very loosely when they say there are five vowels. They mean to say that there are five vowel letters (a, e, i, o, u). Actually, y and w are also used as vowel letters. That is, these seven letters and combinations of them are used to represent vowels. A vowel is something you hear, not something you see. The symbols (letters) you see are not, strictly speaking, vowels. They represent vowels, which is quite different .
There are rather more than five vowel sounds.

HOPE THIS HELPS:)