Java多线程中产生声音的问题

这个我的声音类，

public class Sound extends JApplet{

boolean Baozha = false,Fire = false,Move = false;

AudioClip tankMove = java.applet.Applet.newAudioClip(Sound.class.getClassLoader().getResource("sound/myTankMove.wav"));
AudioClip tankFire = java.applet.Applet.newAudioClip(Sound.class.getClassLoader().getResource("sound/tankFire.wav"));
AudioClip tankBaozha = java.applet.Applet.newAudioClip(Sound.class.getClassLoader().getResource("sound/tankBaozha.wav"));

public void tankBaozha(){
    Baozha = true;
    new Thread(new SoundThread()).start();
    Baozha = false;
}

public void fireZidan(){
    Fire = true;
    new Thread(new SoundThread()).start();
    Fire = false;
}

public void tankMove(){
    Move = true;
    new Thread(new SoundThread()).start();
}

private class SoundThread implements Runnable{
    public void run(){
        if(Baozha){
            tankBaozha.play();
        }
        if(Fire){
            tankFire.play();
        }
        if(Move){
            tankMove.play();
        }
    }
}

}
在其他类中的调用形式为：
Sound aaa = new Sound();
aaa.fireZidan();
但是我发现声音不能同步出现，我不明白这是什么原因，另外，我还想请教如何解决用单独的线程产生声音。