Electronic Voice Phenomena. This is also known as Instrumental Transcommunication which is the collective term for conversing with the Other Side using electronic instrumentation. These instruments include tape recorders, camcorders, telephones, answer machine, radios, televisions, etc.
The sound from other dimensions may or may not be heard when they are recorded but will be heard when you listen to the 'playback'!
I've heard spirits talk to me on a tape recorder.