EVP
Class A
A clear and distinct voice or sound that is universally accepted and undisputed, because it must be understood by anyone with normal hearing and without being told or prompted to what is being said or heard. It can be heard without the use of headphones.
Class B
A voice or sound that is distinct and fairly loud. This class of voice is more common and can be heard by most people after being told what to listen for. It is usually audible to experienced persons who have learned the skill of of listening to Evp. It can sometimes be heard without the use of headphones.
Class C
A faint and whispering voice or sound that can be heard and is sometimes indecipherable and unintelligible. It may have paranormal characteristics, such as a mechanical sound. Most investigators would apply objectivity and disregard it, but may save it for reference purposes.
Class R
In order for an Evp to receive a Class R, rating it must have a meaning when played in reverse.