Class A EVPs are rare and precious finds.
An EVP is "electronic voice phenomena" and this occurs when one is recording under controlled conditions and plays back the recording to hear something said that was not said during the recording session. If a good EVP specialist controls the sound situation and tags every explainable sound heard by his hears, then what he gets on his recordings that cannot be accounted for is exciting territory.
Here are classifications commonly used:
Class A: Voice saying something that, when others hear it without prompting, hearing the same phrase.
Class B: Voice-like, but different listeners might hear different words/phrases.
Class C: A noise.
Since joining the team I'm a part of, I have learned to admire the EVP specialist on the team. He researches extensively, uses logic, and questions everything. I so admire his evidence, that I want you to listen to some of the Class A EVPs he has procured. Listen here.
We still don't understand how EVPs are possible and why. It is very rare we can get a direct answer to a question. There has been question of whether the people in the room might be able to psychically affect the recording with a form of telekinesis. I think the best way to dispute that notion is that we are not getting answers that make sense much of the time. If someone subconsciously imprinted, they would answer the question, not say something nonsensical.
There are some amazing researchers in the field and the one I would recommend highly is David Rountree. He has an impressive technical background and extensive research. In fact, is fantastic book Parnanormal Technology is one of my favs.