you need regular expressions
Like -regex, but the match is case insensitive.
File name matches regular expression pattern. This is a match on the whole path, not a search. For example, to match a file named `./fubar3', you can use the regular expression `.*bar.'
or `.*b.*3', but not `f.*r3'. The regular expressions understood by find are by default Emacs Regular Expressions, but this can be changed with the -regextype option.
find . -iregex ".*\.\(\<mp3\>\|\<flac\>\|\<ogg\>\)"
Changes the regular expression syntax understood by -regex and -iregex tests which occur later on the command line.
Currently-implemented types are emacs (this is the default), posix-awk,
posix-basic, posix-egrep and posix-extended.
find -regextype posix-egrep -iregex "*.*(mp3|flac|ogg)"
easier to write and read
but you could do
find . -iname "*.mp3" -o -iname "*.flac" -o -iname "*.ogg"
search regular expression , for tutorials