Biosonar: Delay and Range

Differences between vision and biosonar

(2) Active vs. passive
Biosonar is an active sense, vision is usually passive. In other words, when using vision, animals use reflections of light waves that are ambient, that is, light that is bouncing around their environment and that is originating from an external source, usually the sun. Animals using biosonar must generate their own sound waves to produce the reflections (echoes) they need. The animal is always actively involved in producing its sonar energy (in the form of pulsed signals). The active nature of biosonar is significant in all sorts of ways, not least of which is the way they judge the range of objects. Range perception is considered to be at the root of biosonar by many scientists, as explained shortly.