There are four audio types: mp3, ogg, wav and aac, aren't there?

Answer 1

the four you learned are the ones supported by html5 i think, @Willian. But there are many more

Answer 2

http://www.nch.com.au/acm/formats.html
I think there are many formats

Answer 3

at least that's what I've learned.

Answer 4

thanks guys, learning is never enough. I sure appreciated the answers, specially ypurs @Awesome. thanks 4 d link.