In order to understand how EVP devices work, you first need to understand how we hear. Humans can hear within the frequencies from 20Hz to 20.000Hz. Clear sounds are usually between the frequencies of 1,000Hz – 5,000Hz. When using recording devices, sounds that are beyond the frequencies of our capabilities can be recorded. Electronic Voice Phenomena (EVP) are sounds, voices, sentences and words that are recorded on these devices but couldn't be heard at the time of recording.
When investigating and trying to communicate with spirit, investigators ask questions and wait for responses. Upon reviewing recordings, investigators listen out for responses to questions that have been asked...
Responses come in many forms such as bangs, taps, words and even sentences! Investigators sometimes receive random responses to questions but are looking largely for intelligent responses that answer questions being asked.