Android studio 播放后如何释放音频

公共类交通扩展了公共活动{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.transportation);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        final ImageView imageView= (ImageView)findViewById(R.id.vatunabussound);
        final MediaPlayer sound = MediaPlayer.create(this,R.raw.vatunabus);
        imageView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (sound.isPlaying()) {
                    sound.pause();
                    imageView.setBackgroundResource(R.mipmap.playicon);
                }
                else {
                    sound.start();
                    imageView.setBackgroundResource(R.mipmap.pauseicon);
                }
            }
        });

        sound.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                sound.release();
                imageView.setBackgroundResource(R.mipmap.playicon);
            }
        });




        final ImageView imageView1= (ImageView)findViewById(R.id.firstbussound);
        final MediaPlayer sound1 = MediaPlayer.create(this,R.raw.varowlsanabus);
        imageView1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                 if (sound1.isPlaying()) {
                    sound1.pause();
                    imageView1.setBackgroundResource(R.mipmap.playicon);
                } else {

                    sound1.start();
                    imageView1.setBackgroundResource(R.mipmap.pauseicon);
                }
            }
        });

        sound1.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                sound1.release();
                imageView1.setBackgroundResource(R.mipmap.playicon);
                }
        });



        final ImageView imageView2= (ImageView)findViewById(R.id.amahmunsound);
        final MediaPlayer sound2 = MediaPlayer.create(this,R.raw.amahmunhahe);
        imageView2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if (sound2.isPlaying()) {
                    sound2.pause();
                    imageView2.setBackgroundResource(R.mipmap.playicon);
                } else {

                    sound2.start();
                    imageView2.setBackgroundResource(R.mipmap.pauseicon);
                }
            }
        });

        sound2.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                sound2.release();
                imageView2.setBackgroundResource(R.mipmap.playicon);

            }
        });

    }
}

在这里，我想在播放后释放音频，这样我就可以播放其他音频而不受干扰，因为有时当我一个接一个地播放音频时，其他音频会播放，但不会产生声音。我用这种方式编写代码，但存在一些问题，例如当我再次尝试播放音频时，我的应用程序会停止