Entity: Whisper Elf

Source Player Core pg. 47 ^2.0

Your ears are finely tuned, able to detect even the slightest whispers of sound. You gain a +2 circumstance bonus when using the Seek action to find hidden or undetected creatures within 30 feet of you. When you target an opponent that is concealed from you or hidden from you, reduce the DC of the flat check to 3 for a concealed target or 9 for a hidden one. This benefit doesn't apply if you can't hear or if the creature is incapable of making sound (for example, if it's affected by a silence spell).