During production, Walt Disney pioneered the use of double tracked vocals for the song "Sing Sweet Nightingale," before it had been used by artists in studio recordings such as The Beatles. When Ilene Woods had completed the days recording of "Sing Sweet Nightingale", Walt listened and asked her if she could sing harmony with herself. She was apprehensive about the idea as it was unheard of; though she ended up singing the double recording, including second and third part harmonies. Ilene Woods reveals the innovation in an interview.
