[6] During the 1950s, Keep provided the synchronization process that allowed Ross Bagdasarian, Sr. to combine his speed-doubled voice technique with full orchestration on "Witch Doctor" and the series of Chipmunks recordings.
Working with the Richard Marino Orchestra, Keep combined custom-built synthesizers and audio signal processing circuits to achieve the unique sounds on the 1961 exotica album Out of This World.
He is also credited with supplying electronic effects on the spooky LP Fantastica: Music From Outer Space, by Russ Garcia and His Orchestra.
Keep is also known for lending his name to the character of Theodore from The Alvin Show and The Chipmunks,[2] and for choosing The Ventures to record the Hawaii Five-O theme.
In addition to the music industry, Keep formed businesses in San Bernardino County, California including an answering service and the Hi-Desert Star newspaper.