The Class A - EVP is a clear voice that can be understood by anyone who listens to it. The Class A will not need to be cleaned up to be understood. A laymen would easily be able to distinguish the Class A. It does not necessarily have to be a loud voice to have this classification, but this is the rarest EVP to capture on any piece of equipment.

The Class B - EVP is a voice that can be discernible by some of those who  listen to it, and will easily agree to what is being said. This kind of EVP is rated as such due to the fact that not all who hear it will be able to agree on what is being said. Some may have to employ the use of headphones, for others, the EVP may have to be cleaned up for them to understand it.

The Class C- EVP   is often not heard by the human ear. It can be a sound or a voice that is not understood easily without a great amount of cleaning or amplifying to be understood, and even then only a few who hear it may be able to understand what they are hearing. In most case this class of EVP will only have one or two words that can be discernible while the rest of what they hear is garbled and unrecognizable.

The Class R- EVP is one other form of EVP and most investigation teams will have their own name for it. This EVP is one that when played normally will be completely unidentifiable, but when played in reverse it will be clearly audible to the naked ear. These too, are as rare as a Class A-EVP, but have been found occasionally in an investigation and since it is so rare it is completely awesome when one is found.