While we're on this subject, did the music have any real purpose? A test pattern and tone are obvious, but why the music?
In Boston, Kaiser/Globe Broadcasting owned both WJIB and WKBG/WLVI (as well as WCAS in Cambridge). In the beginning, the music on Channel 56 during their test pattern periods was from the WJIB music library. They did it to check for tonal quality and to make sure the levels were proper for TV broadcast. Channel 56 generally signed-on after 11:00 AM back in the 60's and early 70's. Eventually, it just became a tradition to put 'JIB music on 56 at the beginning of the broadcast day.
Here's a little sample of WKBG/WLVI back in the day.....http://www.youtube.com/watch?v=eXj0EHiA-X0