I'm using JLayer to play an inputstream of mp3 data from the internet. How do i change the volume of the output?

I'm using this code to play it:

URL u = new URL(s);
URLConnection conn = u.openConnection();  
conn.setConnectTimeout(Searcher.timeoutms);  
conn.setReadTimeout(Searcher.timeoutms);

bitstream = new Bitstream(conn.getInputStream()/*new FileInputStream(quick_file)*/);
System.out.println(bitstream);
decoder = new Decoder();
decoder.setEqualizer(equalizer);
audio = FactoryRegistry.systemRegistry().createAudioDevice();
audio.open(decoder);
for(int i = quick_positions[0]; i > 0; i--){
	Header h = bitstream.readFrame();
	if (h == null){
	    return;
	}
bitstream.closeFrame();