If observers can hear the front room even though they have activated the translation, the cause of the problem seems to be the translator's microphone. The translator's microphone might be picking up output audio, so observers can hear the sound of the front room through the translator.

To change your stereo mix settings:

1. Click on the "Apple" icon.
2. Select "System Preferences".

3. Double click on the "Sound".

4. Click on the "Input" tab.

5. Change the chosen input device to "Internal Microphone".