Meghan Francis

I'm also experiencing this bug. Sound just stops entirely after about 5-10 minutes. I have to restart the client to get it back.

edit: error reports from client:

Client> Error in class 'CodecJOrbis'
Client>     Unable to acquire inputstream in method 'initialize'.
Client>     ERROR MESSAGE:
Client>         minecraft:sound/hal3.ogg
Client>     STACK TRACE:
Client>         bhp.a(SourceFile:37)
Client>         bhx.a(SourceFile:34)
Client>         bhx.a(SourceFile:27)
Client>         biz.getInputStream(SourceFile:65)
Client>         paulscode.sound.codecs.CodecJOrbis.initialize(CodecJOrbis.java:281)
Client>         paulscode.sound.libraries.SourceLWJGLOpenAL.play(SourceLWJGLOpenAL.java:616)
Client>         paulscode.sound.Library.play(Library.java:706)
Client>         paulscode.sound.libraries.LibraryLWJGLOpenAL.quickPlay(LibraryLWJGLOpenAL.java:795)
Client>         paulscode.sound.SoundSystem.CommandQuickPlay(SoundSystem.java:1866)
Client>         paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2438)
Client>         paulscode.sound.CommandThread.run(CommandThread.java:121)
Client> Error in class 'SourceLWJGL OpenAL'
Client>     Audio Format null in method 'play'
Client> Exception in thread "Thread-6" java.lang.NullPointerException
Client> 	at com.jcraft.jorbis.Block.<init>(Block.java:55)
Client> 	at paulscode.sound.codecs.CodecJOrbis.initialize(CodecJOrbis.java:252)
Client> 	at paulscode.sound.libraries.SourceLWJGLOpenAL.play(SourceLWJGLOpenAL.java:616)
Client> 	at paulscode.sound.Library.play(Library.java:706)
Client> 	at paulscode.sound.Library.play(Library.java:675)
Client> 	at paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
Client> 	at paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
Client> 	at paulscode.sound.CommandThread.run(CommandThread.java:121)
Client> 2013-05-23 14:41:24 [CLIENT] [SEVERE] Reached end of stream for /66.85.155.86
Client> 2013-05-23 14:41:26 [CLIENT] [INFO] Stopping!
Client> 
Client> SoundSystem shutting down...
Client> Error in class 'SoundSystem'
Client>     Command thread did not die!
Client> Ignoring errors... continuing clean-up.
Client> Error in class 'SoundSystem'
Client>     Problem during Library.cleanup()!
Client> Ignoring errors... continuing clean-up.
Client>     Author: Paul Lamb, www.paulscode.com

I can't force it to happen, but yes I've experienced this multiple times. Unfortunately it's 100% random. It happens more often with the zombies that spawn on the surface at night than it does with the zombies you find in caves and such. But I've had it happen in both places. It's entirely possible that it's more frequent at night simply because I encounter them more often.