My sister sent me a video of my 7 month-old niece last month singing and humming. I not only thought it was the cutest thing, but I also found it very musical. So like any musically-inclined uncle would do, I sampled it!
 
I made a downtempo track around her vocalizations, and even though I used some Melodyne to correct the pitch, it didn't alter the original audio very much! She pretty much stayed within the key of Db Major all on her own. Her vocalizations even stayed close to the 80 BPM tempo of my track. I didn't have to do any time-stretching on her voice at all. She's not even a year old and she's not just a recording artist, but a songwriter as well (she shares songwriting credit on this one).
 
This song was recorded using Sonar X3 Producer, using mostly Korg Legacy Collection plugins (Wavestation and MonoPoly) and Dimension Pro (the harp countermelody). The drum loop was one of those bundled loops that came with Sonar.
 
https://soundcloud.com/el...ad/egga-featuring-zora]https://soundcloud.com/el...ad/egga-featuring-zora[/link]https://soundcloud.com/elson-trinidad/egga-featuring-zora

I love it.  I think you have done a great job working out her key!  Once you do get a key and progression settled it is amazing how many notes of hers pitch well against the music.  She is talented and signing notes she may have been hearing for a while.  It does not surprise me.  My wife was very pregnant with my son while singing in Jazz vocal ensembles.  He has turned out to be a stellar drummer.  I used to play him tracks like 'Birdland' through headphones pressed on my wifes tummy.  Some killer grooves must have gone in.
 
After he was born we never tip toed around him either. He just slept through endless band, jazz and classical rehearsals and me composing documentary music.
 
I hope you niece gets to hear as much music as she can.  It will all influence her.  If she doesn't end up in the musical world I would be very surprised.

Jeff Evans
I love it.  I think you have done a great job working out her key!  Once you do get a key and progression settled it is amazing how many notes of hers pitch well against the music.  She is talented and signing notes she may have been hearing for a while.  It does not surprise me.  My wife was very pregnant with my son while singing in Jazz vocal ensembles.  He has turned out to be a stellar drummer.  I used to play him tracks like 'Birdland' through headphones pressed on my wifes tummy.  Some killer grooves must have gone in.
 
After he was born we never tip toed around him either. He just slept through endless band, jazz and classical rehearsals and me composing documentary music.
 
I hope you niece gets to hear as much music as she can.  It will all influence her.  If she doesn't end up in the musical world I would be very surprised.

Thanks. Yeah it was kind of easy putting all this together. I didn't have to do much wrangling. In fact I have a much tougher time fixing vocal tracks sung by grown adults! lol
 
My niece lives out in the East Coast, but I did get to visit her last winter when she was a wee 2-3 month-old. I played Christmas music for her on the piano and even rocked her to sleep with some original lullabies. She's quite the little muse!
 
Yeah my niece seems to have music in her blood. My sister took piano lessons for a few years and plays some pieces for her every once in a while. I think she even played her some of my music when she was still in the womb. She tells me the baby enjoys Sarah Vaughn, James Brown and early Jackson Five.  My niece's paternal grandfather also sang and her paternal grandmother taught piano when she was younger. 

Yeah, that was a nice song, made all the more "cuter" with the baby providing the vocals