 Second, a number of philosophers have objected on phenomenological grounds. Audition, they argue, involves experiencing or perceptually representing such spatial characteristics as direction and distance (Pasnau 1999, Casati and Dokic 2005, Matthen 2005, O’Callaghan 2007, 2010). Introspection and performance support the claim that sounds or sound sources are in many ordinary cases perceptually experienced as located in the environment at a distance in some direction. We hear the sound of the knocking over near the door; we hear footsteps approaching from behind and to the left; hearing sound to “fill” a room is itself a form of spatial hearing. Though hearing is more error prone than vision, we frequently do not need to work out the locations of sounds or sources—we simply hear them.