To include a file to be shipped within your deb, go to your qt creator project file and add this:

maemo5 {
MYFILE.files = MYFILENAME
MYFILE.path = /opt/MYAPPNAME/
INSTALLS += MYFILE
}

QtCreator starts looking for your files inside source dir. You must give it full name, estension included.

Throw away QSound, if I don't remember wrong it's not even available on maemo. Use QSound::isAvailable() public static method to check it.