Hello, Lex!
Posting here because I have an identical issue. Running OSX, latest version of Mac Java.
This occurs on a clean installation of Forge with NO mods installed. Forge version is the recommended build here, version 3.3.8.152: (http://minecraftforge.net/forum/index.php/topic,5.0.html)
I am installing Forge, and only Forge into a clean, freshly downloaded vanilla minecraft.jar, deleting META-INF.
The client seems to launch fine and mods seem to play, but the ingame "Options" menu reports the sound to be "OFF" and any attempt to change the slider results in the aforementioned crash.
Forgemodloader-0.log:
Stack trace, reported by Console:
If you require any further information I am more than willing to assist. My suspicion, however, is that the version of the LWJGL that Minecraft ships with is out-of-date.