White noise is controversial.
White noise might provide spirits with sounds (“noise energy”). In theory, ghosts can manipulate white noise to form words on EVP recordings.
I’ve heard remarkable results. This theory might be credible.
It’s the same reason some investigators encourage people to talk normally during EVP sessions. Using software, they can filter out the researchers’ voices. They can highlight anomalous sounds and ghostly voices, too.
Ghosts might use, manipulate, or recycle ambient noise to communicate with us.
A few ghost hunters believe white noise might provide a wall or background. Against that, ghosts feel confident that their words can be heard.
To me, that seems unlikely, but I could be wrong. I’m just guessing. In this field, most of us are.
Sure, white noise and other audio input might your EVP recordings, but – as of late 2016 – scant scientific evidence exists. So, it’s best to test it yourself, and see if the results are worthwhile… and credible. (This applies to all real-time communications with spirits, recorded electronically.)
You can download white noise free (or at low cost) at sites like rain.SimplyNoise.com.
Other inexpensive apps can generate white noise to use during EVP sessions. You’ll probably find several for your phone or other devices.
Also, experiment with other “colors” of noise at http://mynoise.net/NoiseMachines/whiteNoiseGenerator.php (Try noise calibrated with more brown or pink in it.)
You may prefer Coffitivity.com. It’s not white noise, but it could be a good background for your EVP sessions. Just be sure the Coffitivity voices aren’t saying anything you might confused with actual EVP.
If specialized noise makes a dramatic difference, use it. If it doesn’t, don’t bother with it.
Note: Some team members are distracted by certain noises. So, be sure to check with them before conducting too many tests.