If I run with oracle jre 1.6.0_31, i get the following stack trace too and I don't have audio, but the game doesn't crash.

Starting up SoundSystem...
Initializing Java Sound
    (The Java Sound API.  For more information, see http://java.sun.com/products/java-media/sound/)
JavaSound initialized.

Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)
Error in class 'SourceJava Sound'
    Channel null in method 'stop'
Error in class 'ChannelJava Sound'
    Unable to attach buffer to clip in method 'attachBuffer'
    ERROR MESSAGE:
        line with format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian not supported.
    STACK TRACE:
        com.sun.media.sound.DirectAudioDevice$DirectDL.implOpen(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.implOpen(Unknown Source)
        com.sun.media.sound.AbstractDataLine.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        com.sun.media.sound.DirectAudioDevice$DirectClip.open(Unknown Source)
        paulscode.sound.libraries.ChannelJavaSound.attachBuffer(ChannelJavaSound.java:278)
        paulscode.sound.libraries.SourceJavaSound.play(SourceJavaSound.java:311)
        paulscode.sound.Library.play(Library.java:706)
        paulscode.sound.Library.play(Library.java:675)
        paulscode.sound.SoundSystem.CommandPlay(SoundSystem.java:2076)
        paulscode.sound.SoundSystem.CommandQueue(SoundSystem.java:2599)
        paulscode.sound.CommandThread.run(CommandThread.java:121)