AudioManager manager = (AudioManager)getSystemService(Context.AUDIO_SERVICE);
Log.d(TAG, "ATTACHED: " + manager.getParameters("attached_output_devices"));
Log.d(TAG, "DEFAULT: " + manager.getParameters("default_output_device"));
Log.d(TAG, "PRE: " + manager.getParameters("audio_devices_out_active"));
manager.setParameters("audio_devices_out_active=AUDIO_DEVICE_OUT_AUX_DIGITAL");
Log.d(TAG, "POST: " + manager.getParameters("audio_devices_out_active"));
audioManager = (AudioManager) getApplicationContext().getSystemService(Context.AUDIO_SERVICE);
audioManager.setParameters("audio_devices_out_active=AUDIO_CODEC");
// or
audioManager.setParameters("audio_devices_out_active=AUDIO_HDMI");
// or
audioManager.setParameters("audio_devices_out_active=AUDIO_HDMI,AUDIO_CODEC");