Some ICDs have a feature called Patient Alert. If this feature is turned on, the device will sound intermittently (an on/off, high/low pattern) for 20-30 seconds if something is wrong with its settings. It's a little robotic cry for help. You should contact your doctor to have your device tested as soon as you can. The tones will continue to turn on at about the same time each day until the settings are adjusted. In addition, the Patient Alert feature can play a solid tone if your device is nearing a magnetic field. That's just a warning to stay away from magnetic stuff.