Mapping Center Answer:

If I understand this right, you want to see something in the TOC and on the map (as the TOC is just an inventory of the kinds of things that will be drawn on the map).  If you've got an attribute that describes the sound, say in terms of decibles (or relative loudness), or duration of the sound, then you could create graduated symbol or color symbology on such fields. If it the type of sound, e.g., "beep", "honk", or "squawk" is an attribute, then you could use unique values symbology.

This also depends on whether the map is meant to be something of a discovery tool, or that a map reader is meant to be promted, through symbols to the sounds they want to hear.  If the former, you might not draw the features that cause the sounds at all, but you could use any of the above methods, just using symbols with "no color", which would give you a legend, giving users an inventory of what they should be finding, without tipping them off.