You are adapted to a subterranean environment.
Prerequisite: Underground as sole environment type.
Benefit: Living underground has made you more reliant on nonvisual senses than surface dwellers. You gain a +2 competence bonus on Listen checks and a +4 competence bonus when tracking by scent.
Source: Savage Species, page 32. Changed “General” descriptor to “Background”. Changed “terrain type” in Prerequisite to “environment type”.