Simultaneously recorde from two mics and play it back to one speaker in java

Test.java

import javax.sound.sampled.*;

public class Test {
    
    private static final AudioFormat FORMAT = new AudioFormat(48000, 16, 2, true, false);
    private static final DataLine.Info MIC_INFO = new DataLine.Info(TargetDataLine.class, FORMAT);
    private static final DataLine.Info SPEAKER_INFO = new DataLine.Info(SourceDataLine.class, FORMAT);
    
    public static void main(String[] args) throws LineUnavailableException {
        final TargetDataLine micro1 = findMicrophoneOrUseDefault("name");
        openTargetLine(micro1);
        
        final TargetDataLine micro2 = findMicrophoneOrUseDefault("name");
        openTargetLine(micro2);
        
        final Mixer speakerMixer = findMixer("", SPEAKER_INFO);
        
        final SourceDataLine speaker1 = (SourceDataLine) speakerMixer.getLine(SPEAKER_INFO);
        openSourceLine(speaker1);
        
        final SourceDataLine speaker2 = (SourceDataLine) speakerMixer.getLine(SPEAKER_INFO);
        openSourceLine(speaker2);
        
        final byte[] buffer1 = new byte[960 * 2 * 2];
        final byte[] buffer2 = new byte[960 * 2 * 2];
        
        while (true) {
            micro1.read(buffer1, 0, buffer1.length);
            micro2.read(buffer2, 0, buffer2.length);
            
            speaker1.write(buffer1, 0, buffer1.length);
            speaker2.write(buffer2, 0, buffer2.length);
        }
    }
    
    private static void openTargetLine(TargetDataLine line) {
        try {
            line.open(FORMAT, 960 * 2 * 2 * 4);
            line.start();
        } catch (LineUnavailableException ex) {
        }
    }
    
    private static void openSourceLine(SourceDataLine line) {
        try {
            line.open(FORMAT, 960 * 2 * 2 * 4);
            line.start();
        } catch (LineUnavailableException ex) {
        }
    }
    
    public static Mixer findMixer(String name, Line.Info lineInfo) {
        Mixer defaultMixer = null;
        for (Mixer.Info mixerInfo : AudioSystem.getMixerInfo()) {
            final Mixer mixer = AudioSystem.getMixer(mixerInfo);
            if (mixer.isLineSupported(lineInfo)) {
                if (mixerInfo.getName().equals(name)) {
                    return mixer;
                }
                if (defaultMixer == null) {
                    defaultMixer = mixer;
                }
            }
        }
        return defaultMixer;
    }
    
    private static TargetDataLine findMicrophoneOrUseDefault(String name) {
        try {
            for (Mixer.Info info : AudioSystem.getMixerInfo()) {
                final Mixer mixer = AudioSystem.getMixer(info);
                if (mixer.isLineSupported(MIC_INFO) && info.getName().equals(name)) {
                    return (TargetDataLine) mixer.getLine(MIC_INFO);
                }
            }
            return (TargetDataLine) AudioSystem.getLine(MIC_INFO);
        } catch (LineUnavailableException ex) {
            return null;
        }
    }
    
}