Catching up on my Email from home, so this may include static.

Robbie Rhodes mentions the  NBC chimes as  an example of  a sound
pattern  given  patent  and  trademark protection,  going  on  to
discuss how the sound was produced.  I  read recently in  one  of
the old-time radio publications an article on  that  very  topic.
If there is interest in it, I'll try  to find the article.  As  I
recall, some NBC engineer made a little chime set that was struck
automatically.   Later   they   switched   to   electronic   tone
generation.

How many people have ever heard the  NBC "fourth tone," which was
used to signal an upcoming announcement of great importance?  NBC
preceded its announcement of VE-day or  the end  of WWII with the
four-tone chime.   For  those  of  us  who  heard  the three-tone
pattern day in and day out, it was  a real awake call to hear the
four tones come over the radio.