This may be very elementary but one of those things you need to be taught at least once. Its a very quick and easy way to get an effective “scary” voice for Halloween audio. Anyone with any sort of DAW can do it. All you need is pitch shift. I explain in audio form below with examples but here is a quick run down.
Take any dry VO audio. You will triple it up on three tracks. All playing at the same time. Leave one dry and unchanged. The second should be pitched down and the third should be pitched up. When played back simultaneously it has a cool effect and it only takes you seconds to get the effect done. Happy Halloween!