Although Echo-BlindDog’s sound emissions are outside the frequency of human hearing, you can verify proper operation by following these steps: – Make sure the regular blue visual indicator is present, indicating that the program is working properly. – Take your cell phone and launch your sound recording application. – Place your phone’s microphone approximately 1 cm from the Echo piezoelectric transmitter you wish to test. – Record for approximately 30 seconds. – Restart the broadcast of the recording. – When streaming the recording to your mobile phone: If you hear the audible clicks, this confirms that the case is working properly and emits the beeps. You can use this cell phone as a “reference phone” for all future checks that the case is functioning properly. If you are unable to hear the clicking sounds, your phone microphone may not be able to record the frequency emitted by Echo-BlindDog. Repeat with a different phone model until you find a “reference phone” that can record Echo-BlindDog’s sound frequency. Note: We recommend defining a reference telephone upon receipt of Echo-BlindDog. This will allow you to ensure that your dog’s enclosure is completely functioning properly during future checks.