Ultrasound
Videos
Ultrasound is sound with frequencies greater than 20 kilohertz. This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic wave
An ultrasonic examination
Galton whistle, one of the first devices to produce ultrasound
Bats use ultrasounds to navigate in the darkness.
A dog whistle, which emits sound in the ultrasonic range, used to train dogs and other animals
Animal echolocation
Videos
Echolocation, also called bio sonar, is a biological active sonar used by several animal groups, both in the air and underwater. Echolocating animals emit calls and listen to the echoes of those calls
The especially long tails on the hindwings of the African moon moth, a Saturniid, oscillate in flight, deflecting the hunting bat's attack to the tails and thus enabling the moth to evade capture.
