set visible-bell ignored

[J Krugman]

Despite the fact that I have

  (setq-default visible-bell t)

in my Emacs init file, and that C-h v visible-bell confirms that
it is indeed t, my Emacs still beeps at every opportunity it gets.
It's driving me insane.  My zsh, on the other hand, responds as
desired to "setopt no_beep".  Ba-a-ad Emacs!

Does anyone know why Emacs would disregard the visible-bell setting,
even when the terminal is perfectly capable of being silent?

TIA,

jill
-- 
To  s&e^n]d  me  m~a}i]l  r%e*m?o\v[e  bit from my a|d)d:r{e:s]s.