yes you have to hear it, but it has been answered that you can listen to sapien medicine audios while also listening to your own music. i would just make sure i can also hear sapien medicine’s audios at least a little bit.
others have also mentioned that you can play them on different sources like your music on your phone speakers and sapien medicine audios on your computer speakers and vice versa.
No. You don’t even have to hear it. It’s been confirmed by on the official FAQ here. As long as it’s in your hand or pocket, somewhere very close to your body. It will work even at low volume. The sound carries the energy, not the volume