Class A: Class A EVPs are the highest quality EVPs. They are easy to understand and the majority of people agree on what is being said.
Class B: Class B EVPs are EVPs in which there is clearly something being said. However, not all people are in agreement on what is being said.
Class C: Class C EVPs are EVPs that are extremely difficult to hear and often require the use of headphones. This class of EVP is not considered as evidence by the majority of paranormal researchers.