ASIFA offers up this in-depth history of the Chipmunks.
Ross Bagdasarian Sr. (who went by the stage name "David Seville")....bought a tape recorder with his last $200 and played around with shifting the speeds, coming up with a novelty song titled "Witch Doctor". He got the single released and two weeks later, he found himself appearing on the Ed Sullivan Show performing the song....The success of "Witch Doctor" gave him the idea of creating characters with sped up voices, so he quickly knocked out a Christmas demo titled "The Chipmunk Song" and took it to record executives Simon "Sy" Waronker, Theodore "Ted" Keep and Alvin "Al" Bennett at Liberty Records. The label was close to bankruptcy, but Bagdasarian convinced them that they might as well press Chipmunk singles with the leftover vinyl pucks and labels in their warehouse rather than just turn the unused stock over to the bank when the business went under. Production commenced and in just a few months leading up to Christmas of 1958, the record shot to the top of the charts, becoming one of the best selling singles of all time.