[CM] Finding (and deleting) gaps with snd

[Bill Schottstaedt]

By "zero" do you mean zero-crossing?  There are several functions to search for these
(find-zero in extsnd.html for example) -- you could use the crossing locations to
set the limits on (scale-by 0.0 ...).  If you're looking for sections without any
real signal, perhaps map-silence in extsnd.html will help -- it detects portions
that look like silence, then either squelches whatever hiss is there, or deletes
that section altogether.