'I have writers that I write with, or I have writers that will send me a full song, and I'll rearrange it - change the second verse, change the melody, keep a chord that I like, and recreate it. Just depends. I might bring in whoever I think can help the song. When I have just a beat it's the most fun for me. I'll get somebody to play whatever I hum for the bassline. So I'm creating a whole track with my voice.'
http://www.telegraph.co.uk/culture/music/3563004/Beyonce-dream-girl.html