I was underleveled (16) when I finally got to Alduin last night. Also ran into the glitch where he couldn't take damage. So I ran away. Problem now is that the rumbling storm sound that plays during his fight is playing EVERYWHERE and overpowering everything, even underground in Riften. Only menus make the sound die off, but it comes right back when returning to active gameplay. My copy is Vanilla with no DLC. Any help is appreciated.
Since you haven't saved before your encounter with Alduin, your best bet is to wait for another dramatic cinematic event to overload the current audio playing script and reset it (that's just my hypothesis) or reboot your system. The only other way would be to make a new save or reinstall the game.