download the app frequensee for your phone and make sure the volume isn't over -30 DB from where you're located
but aside from that ultrasonics can go great distance, as long as you have a decent DB level at your ears you will be fine. If you can get them on the sides of your ears for the stereo effect it's even better.
but aside from that ultrasonics can go great distance, as long as you have a decent DB level at your ears you will be fine. If you can get them on the sides of your ears for the stereo effect it's even better.
