The Womb Music Belly Speaker and gel pad is the only thing that is in contact with the mother's belly.The speaker doesn't have anything but the sound coming out of it so it's very safe for both you and your baby.The Womb Music Bluetooth Controller also does not emit radiation of any sort. It uses Bluetooth, similar to the type of headset/earbud you would use on your head, to connect to your phone. While this is also very safe,  the controller is not in contact with the mother's belly so is not a concern for the baby.