When you start Minecraft in Alpha Version I use alpha1.1. You have no sound. In the Console you got following Exception:
Client> java.lang.StringIndexOutOfBoundsException: String index out of range: -1
Client> at java.lang.String.substring(Unknown Source)
Client> at bf.a(SourceFile:66)
Client> at bf.run(SourceFile:39)
I hope you can still fix it.
Sorry for lying with the version.