Which term refers to the detection of objects by emitting sound and listening for echoes?

• A. Sonar
• B. Side-Scan Sonar
• C. Sound
• D. Sofar

Answer: (A)

Detecting objects by emitting sound and listening for echoes is called sonar. In underwater contexts, a transducer sends out a sound pulse and waits for echoes to return; the time it takes for the echo to come back lets us calculate distance, while the echo’s strength and characteristics help infer size and composition. Side-Scan Sonar is a specific application of sonar that sweeps the sides to create images of the seafloor, so it’s still a type of sonar but more specialized. Sound, simply, is just vibrations traveling through a medium and isn’t itself a detection method, and Sofar refers to a historical long-range signaling system rather than the general technique of detecting objects via echoes.