A further explanation:
This is the sound of the squares going across the screen, which they
used as a transition. The scripts made reference to an "idling
pattern"...which I always thought was the squares transistion.
The file is called "idling pattern.wav"
Wasn't until I saw the episodes again that I realized the idling
pattern was the effect you see, such as in this clip on the web site.
But old habits are hard to break...and I didn't know what else to call