The purpose of the White Noise EM is to make EVP’s more audible during paranormal investigations. The white noise is created as an electromagnetic signal instead of a conventional auditory signal. Therefore you do not hear the white noise, increasing the chance of a clearly understandable EVP. An inductive microphone is needed in order to listen to the EVPs. The device is charged with the USB to USB Mini cable which can be plugged into any computer or USB port. It is not compatible with a phone charging cable. A green or blue light will show when charging is complete.