There are three patches out for Spore. They have to be installed individually, so if you're starting from the disk, you'll see three 'There's a patch available' messages in a row, followed by a patch each time.
I would delete the game, reinstall it from the disk, then just click 'OK' through the various patches. Note that the patches take a long time to run (about as long as the initial install), and that the first patch does not provide a great progress indicator; during patching of some of the big files it will just sit there for a long time. Don't force quit it half way through! That will lead to the audio issue you're describing, since the audio file is the big one that takes a long time to patch.
