I'm also having the same problem with my PPC G5 PowerMac running 10.4.11. I had the version 1.3.x and upgraded to 1.4.2 last night. Now all sounds are static and very loud. I immediately deleted the minecraft folder in the apps support folder and went back to my previous backed up minecraft folder for 1.3.x. So while I can still play the older version with working audio, I'm eagerly awaiting a fix for the newer version.
Anthony Bailey
I'm also having the same problem with my PPC G5 PowerMac running 10.4.11. I had the version 1.3.x and upgraded to 1.4.2 last night. Now all sounds are static and very loud. I immediately deleted the minecraft folder in the apps support folder and went back to my previous backed up minecraft folder for 1.3.x. So while I can still play the older version with working audio, I'm eagerly awaiting a fix for the newer version.