how did they do the voices for alvin and the chipmunks
The voices of the group were all performed by Bagdasarian, who sped up the playback to create high-pitched voices. This oft-used process was not entirely new to Bagdasarian, who had also used it for two previous novelty songs, including "Witch Doctor", but it was so unusual and well-executed it earned the record two Grammy Awards for engineering. Bagdasarian, performing as the Chipmunks, released a long line of albums and singles, with "The Chipmunk Song" becoming a number-one single in the United States. After Bagdasarian's untimely death in 1972, the characters' voices were performed by his son Ross Bagdasarian Jr. and the latter's wife Janice Karman in the subsequent incarnations of the 1980s and 1990s.