It's hard to tell in advance what's news in this business and what's known, but here is a little maneuver I came across for avoiding that hard-coded "wzzh" sound for an item that runs out of charges or otherwise expends itself. In properties, "When drained," instead of "Item vanishes" choose "Replaced with used up" but don't enter anything into the "Used up item" field on the main page. The item will quietly remove itself. You must set the number of charges to some number other than 0 for this to work, though.
There is a variation on this technique for temporary items that vanish with that sound, like magic weapons. Put a Delay/Permanent effect in their properties, timed to a second before their normal expiration time, with Remove Inventory Item, and they will go quietly (and without a message). This effect removes the whole batch of the item in question. Not a problem for unequippable magic weapons, unless you've conjured them over several castings and want them to fade away in succession as well. I don't know if this effect will take away all of several stocks of the item split in the inventory or only the first one it finds.