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Biosonar: Range and Delay

Consider the differences between using vision and using biosonar. They are both used to build images of an animal's surroundings, but they are different in so many fundamental ways. This can make biosonar unexpected and paradoxical, because it is so different to senses we are more familiar with. Here are some of the most important differences between biosonar and vision.

(1) Sound waves vs. light waves: Speed and distortion
As you already know, when animals use biosonar to form images, they use sound waves, while animals using vision make use of light waves. Sound waves travel much, much slower than light waves. The speed of sound waves is about 343 m/s (metres per second), while that of light is more like 3 million m/s. The slow speed of sound waves means that animals can experience delays of vital milliseconds (thousanths of a second) in updates of biosonar information, as the animals wait for the sound waves to return. This might not seem important, but it is if you are trying to intercept a fast and erratically flying insect in mid-air! Also because of the slow speed of sound waves, animals can experience distortion of their sonar signals, therefore of their sonar images, by the Doppler Effect.