The title refers to the Christmas hymn - "Do you know the song that the angels sang"
Do you know the song that the angels sang On that night in the long ago, When the heavens above with their music rang Till it echoed in the earth below?
I used the following sample from The Freesound Project (www.freesound.org): http://www.freesound.org/people/genghis%20attenborough/sounds/36222/