What is the symbol that denotes vowel sound called?

There isn't a single symbol that specifically denotes vowel sounds. Instead, we use a combination of symbols and diacritics depending on the specific phonetic alphabet we're using.

Here are some examples:

* International Phonetic Alphabet (IPA): This is the most widely used phonetic alphabet. It uses different symbols for each vowel sound, like /ɑ/, /e/, /i/, /o/, /u/, and many more.

* Other phonetic alphabets: Other phonetic alphabets, like the Americanist phonetic notation or the Wells' lexical sets, also use their own specific symbols for vowel sounds.

Therefore, there isn't a singular symbol that denotes vowel sounds in general. It's important to specify the phonetic alphabet being used to understand the meaning of the symbols.