A stable Bluetooth working distance depends on a lot of factors such as the environment and your phone. In a “busy” wireless environment where there are many phones and WIFI devices, the Bluetooth connection could be interfered. Our recommended working distance is 2 meters, within which Stemoscope normally works well based on our test. For the best Bluetooth performance, you may minimize the distance between your phone and Stemoscope and keep a line of sight between the device and the phone.