12 Days of Christmas (1956) - Who Was That Singing Voice?

One of the most popular videos on the Children's Media Archive YouTube Channel is "The 12 Days of Christmas" (1956). From research, this short is either a 5 minute special that aired on CBS before midnight, an episode of the Gerald McBoingBoing Show or a UPA cartoon produced for the Columbia Broadcasting System (CBS). To date, it is still unverified which one it could be. Further research suggests that this short fell into the public domain in 1984. 

One leading excellent question in the comments section is who was the singer in this short? Whoever it was had an excellent singing range. Their voice, with the animated visuals has been a part of many people's childhoods for 65 years.

Documentation of the singer has to exist, possibly in records belonging to CBS or the animation studio that produced the short.

If you have any information on this short film, and/or the woman singing the vocals please leave a comment below. You can also write archivebuilder@gmail.com with "12 Days of Christmas" as a subject.