I haven't hunted that unit but I just keep an eye out for them and listen for the rattle. I still have yet to see one in the wild too!
hahahahahaha that is absolutely hilarious on my behalf. To paraphrase the guy from Christmas Vacation:
I couldn't hear a dump truck drive through a nitroglycerin plant. Hell, I've had the old buzz tail waving his or her tail within a couple of feet of me and I did not hear a thing. I've topped out on rock climbs in Tieton, WA where the damn things were nearly in my face and did not hear them, BUT

I saw them !!!!!!!!!!
No if you got good ears then that works, just ask my wife.