Echo emits sounds outside the frequency of human hearing, so you won’t be able to hear it! In order to test the correct functioning of the box, you must: Check for the regular blue visual indicator which tells you that the program is working correctly!  Check that the sound transmitters are working using the “reference cell phone” method. Note: all other “blue” visual operating indicator sequences indicate a malfunction. You must then remove Echo-blinddog from your dog and contact us via the contact form describing the blue light sequence.