Keen-Eared Scout( Player's Handbook II, p. 80)
Your sharp sense of hearing allows you to determine much more about your surroundings.
When you make a Listen check, you might learn more than normal about a source of noise.
If you beat the Listen DC by 5 or more, you determine the size, speed, and direction of the source of noise.
If you beat the DC by 10 or more, you determine the precise, current position of the creature or object that caused the sound.
If you beat the DC by 15 or more, you determine the type of armor the creature wears and what it carries, if anything.
If you beat the DC by 20 or more, you learn the creature's type and subtypes.
The information you learn is cumulative. For example, if you got a Listen check result of 35 against a DC of 23, you gain the information for beating the check by 10 and by 5. These benefits apply to both standard and opposed Listen checks.
Also, you gain a +5 bonus on Listen checks to pinpoint invisible creatures.