Layering can be done with one singer or many.
The advent of multitrack recording opened new possibilities for sonic texture. One of the first uses of overdubbing was the double tracking of voices to give a new sound and also to help voices that were weak on their own. Soon, layers and layers of voices were added as their own effect, turning a solo artist or small group into a huge choir. Queen's "Bohemian Rhapsody" stands as a stunning example of what vocal layering can accomplish.
Prepare Tracks
Layering will frequently require a large number of tracks to be recorded quickly, so the process runs more smoothly if your recording equipment is set up before. Name the tracks as a planning guide (Alto 1, Alto 2, etc.). Prepare nine to 12 tracks and be ready to re-patch and re-arm tracks. Planning at this stage will keep you organized and will avoid accidental erasure as you move through the process.
Begin Recording
At this stage, record vocals free of equalization, compression or reverb. If you have a selection of microphones, choose one that has a slightly thin sound to make mixing easier later. To create nine layered tracks, for example, you will record three separate takes of one melody line, three takes of a first harmony and three more takes of a second harmony. You are restricted to layers only by the number of tracks available.
Recording Alternative
Another way to create a layered sound is to set three microphones at three different distances from the singer. To prevent comb filtering and phase issues, set microphones at six inches from the singer, 18 inches and five feet. Each mic will capture a different amount of room sound. One singer will need to record only three passes to create nine tracks. The effect will be different than nine passes, but may be suitable. Combine the techniques and you end up with 27 tracks of vocals.
Mixing
The possibilities for mixing the layers of vocals are endless. There are a few rules of thumb that may serve as a starting point. Aggressive low frequency roll off, extending into the low midrange, is often a good idea so that the layers don't mask or muddy the rest of your mix. Likewise, added reverb should be equalized to de-emphasize low frequencies. Aggressive compression can sometimes make the layers distinct without being loud. Panning works with the layers spread or coming from the same point. Try both and see what works with your project.
Other Tips and Tricks
Group layers together by part so that you can change levels to all tracks with that part at once. If your layered project is an a cappella song, use little equalization and use compressors with care to keep the sound natural. Layered voices can sometimes over-emphasize plosives, letter sounds like "P" and "T." Digitally edit the offending sound off of two of the three tracks of each group.
