3e SRD:Listen Skill
From D&D Wiki
|This material is published under the OGL|
Make a Listen check against a DC that reflects how quiet the noise is that the character might hear or against an opposed Move Silently check.
The DM may make the Listen check so that the character doesn't know whether not hearing anything means that nothing is there, or that the character rolled low.
|5||A person in medium armor walking at a slow pace (10 ft./round) trying not to make noise.|
|10||An unarmored person walking at a slow pace (15 ft./round) trying not to make any noise|
|15||A 1st-level rogue using Move Silently within 10 ft. of the listener|
|19||A cat stalking|
|30||An owl gliding in for a kill|
|+1||Per 10 ft. from the listener|
|+5||Through a door|
|+15||Through a stone wall|
In the case of people trying to be quiet, the listed DCs could be replaced by Move Silently checks, in which case the listed DC would be the average result (or close to it).
The character can make a Listen check every time the character has a chance to hear something in a reactive manner. As a full-round action, the character may try to hear something the character failed to hear previously.
When several characters are listening to the same thing, the DM can make a single 1d20 roll and use it for all the listeners' skill checks.