See:

• Animal echolocation: animals emitting sound waves and listening to the echo in order to locate objects or navigate.
• Human echolocation: the use by blind people of sound to navigate.
• Sonar: (sound navigation and ranging) the use of sound to navigate or to locate other watercraft, usually by submarines.
• Echo sounding: listening to the echo of sound pulses to measure the distance to the bottom of the sea, a special case of Sonar.
• Medical ultrasonography: the use of ultrasound echos to look inside the body
• Radar is an acronym for radio detection and ranging