After experimenting with this device, I've found it to be….wonky at best.
My suggestion would be to give it a look, and make it so it can record everyone talking in a room be it in your hand, in your inventory, or hidden in a room.
So far I've found that sometimes it will record you if you speak directly to it. Sometimes it won't.
Somtimes It will record a shout too.
Improving this would be great for detective types and blackmailer types.
BATA