  There are other blind people who know objects in their physical environment by echolocation, having cultivated the skill of making clicking noises with their tongues and identifying the different qualities of sounds bounced back toward them (Tresniowski and Arias 2006 [in Other Internet Resources]; see also “Shattering Barriers” at the World Access for the Blind website, in Other Internet Resources).  Belgium's police force includes blind detectives who can listen to criminals' recorded conversations and by the reverberations of sound identify what kind of room they occupy, whether they are using a landline or cell phone, and even what kind of car they are traveling in or whether the suspect's Flemish carries an Albanian rather than a Moroccan accent (Soares 2007). Sighted people's typical lack of functional ability to navigate by reverberated sound, and thus their inferior way of knowing the absorption/reflection properties of the physical objects that surround them, and their deafness to nuances of spoken sound, surely should be recognized as a disadvantage.  Yet this is almost never so, even where sighted people must find their way in the dark or distinguish among interlocutors beyond their vision.