Characters with this skill may move through urban environments almost silently. Listen tests made against the character will be at -10% on the basic chance. This applies to all of the actions given on the hearing table - including opening doors, searching, talking, and so on.
Urban environments are basically all built-up areas. The skill also applies to the insides of buildings in general, even if they are in a rural setting; farm buildings, for instance. At the gamesmaster's discretion, this skill may additionally apply to certain underground situations, especially in the case of artificially constructed rooms and passages.