Investigators have tried a variety of ways to obtain EVP or to aid the spirit in communication via auditory methods.
Some investigative groups believe that making available sounds such as white noise (noise similar to the static on a poorly tuned analog television) that the spirit can use will help. Some have experimented with White, Pink and Chrome noise. Sometimes there seems to be preference for one over another, but this does not seem to give the same positive results in varied circumstance or locations.
Others have insured that there is mechanical noise (a refrigerator or other constant noise) or used an “EVP generator” for the same purpose. It is unclear however, that there is any definite method to insure EVP or the improved quality that those in the field are looking for.
In the more recent years people have started investigating with Pink noise, chrome noise and others. The feedback on each of them is still out with the jury though.