Psychologist Lawrence Rosenblum has written an excellent short article about a remarkable group of blind mountain bikers who apparently use echolocation to avoid obstacles by making loud click sounds as they ride.
Rosenblum has studied human echolocation in the lab and has shown that we all have some ability to get an idea of the spatial layout of our environment from sound reflection.
But one of the most interesting bits is where he discusses the fact that while echolocation uses sound, we don’t always process it as a conscious hearing experience. It can seem to just be a ‘sense’ of where objects are.
To get a sense of how echolocation works, try this. Hold your hand up about one foot in front of your face with your palm facing your mouth. Put your front teeth together, open your lips, and make a continuous shhhhhh sound. As you make this sound, slowly bring your hand toward your mouth. You will hear the shhhh sound change. What you‚Äôre hearing is the sound reflecting from your hand colliding with the sound leaving your mouth. This interference turns out to be one of the most important types of sound dimensions we use to echolocate objects at close distances.
But this demonstration is exaggerated. The interference patterns used for echolocation are usually too subtle to be consciously heard. This highlights one of the most amazing aspects of echolocation: It‚Äôs rarely experienced as sound. Try using your shhhh sounds to walk slowly toward a wall with your eyes closed. As you come close to the wall, you‚Äôll experience its presence as more of a feeling than a change in sound. It may feel as if there are air pressure changes on your face, an experience also reported by the blind (echolocation was once called ‚Äúfacial vision‚Äù). Echolocation is truly one of your implicit perceptual skills: It allows you to detect aspects of your environment without even knowing which sensory system you‚Äôre using.