• Using SndControl

Put SndControl in your System Folder, restart the Mac and call up the Control Panel. You'll be confronted with a number of radio buttons and check boxes, plus a list of sounds and a volume control slider. Relax, SndControl is much easier to use than it may appear to be at first sight.
By default, the Beep radio button is selected and the setting of the Volume slider will match that of the slider in Apple's General (system 6 only) and/or Sound control panels, that is, it will correspond to the current volume setting stored in the battery backed "parameter ram".
Note that changing the volume setting with SndControl when the Beep radio button is selected is equivalent to changing it with either of the aforementioned control panels.

The list of sounds will show any sounds (that is, resources of type 'snd ') contained in the System file plus those that you may have put in a sound suitcase file named "snd" (created using Sound Mover, more on this later) plus those found in any sound suitcases or other files that you have opened with Suitcase ™, Master Juggler™ or CarpetBag. Note that for SndControl to find it, the "snd" file must reside directly in the System Folder, rather than in a folder within the system folder.
To find out what sound is currently associated to a given event, push the corresponding radio button and the name of the sound will be highlighted in the list.
The first time you use SndControl (or any time you trash its Prefs file), the Beep sound will be set to Simple Beep (actually, to the 'snd ' with a resource id of 1, assuming there is one) and all other events will be set to the line at the top of the list of sounds that says "No sound", i.e. to silence.
Above the eight radio buttons on the left, you'll see a two-headed arrow: 

clicking its left or right head will cause the radio buttons to be renamed to correspond to a different set of events.