Apple issued an update to Mountain Lion 10.8.4 this week which I applied via system update. This left my hackintosh probook 4540s without sound and also removed the battery status indicator from the menu bar.
After a bit of investigation I found this was easily fixed by re-running the Probook installer from the tonymac site. I downloaded the latest version, since there had been several updates since I did my initial install a few weeks ago, and was initially confused because I couldn’t find anything in the various options which referenced audio. After several attempts I found that the option to run is the option “OS X Support Kexts -> 4x40s -> Mountain Lion -> 10.8.3”. This was not obvious because I’m actually running 10.8.4, but it works and after a reboot the audio / battery indicator is now back and running properly.