This app produces sound waves with frequencies in the range of 18000 Hertz to 19000 Hertz. These frequencies are inaudible to most humans, but can be played through broadcast media and picked up by nearby smart devices. This method allows detecting that one device is in the proximity of another at a particular time, and lets measurements be collected that indicate such things as a particular television commercial having been viewed or a that a particular pair of smart devices belong to the same owner. For those who dont prefer to have their device habits or their media consumption patterns tracked, this app lets you add ultrasonic noise to a room in the same frequency range as that of the measurement signals, with the goal of creating a sonic firewall in the form of noise that can act as a gateway under your control for tracking data transfer between devices.