Sonar is a relatively recent invention by man for locating objects under water using sound waves. However locating objects in water and air has evolved in the biological world to a much higher level of sophistication. Echolocation, often called biosonar, is used by bats and cetaceans (whales, manatees, dolphins etc.) using sound waves at ultrasonic frequencies (above 20 kHz). These animals use sound to survive and have greatly superior capabilities to current engineering technology with regard to resolution, object identification and material characterisation.

Based on the frequencies in the emitted pulses, some bats can resolve targets many times smaller than should be possible. They are clearly processing the sound differently to current sonar technology. Dolphins are capable of discriminating different materials based on acoustic energy, again significantly out-performing current detection systems. Not only are these animals supreme in their detection and discrimination capabilities, they also demonstrate excellent acoustic focusing characteristics - both in transmission and reception.