Question

The device which is not based on the reflection of sound is

• A. Megaphone
• B. Galton's whistle
• C. Sonar
• D. Stethoscope

Answer 1

The correct option is B Galton's whistle

Megaphone: A megaphone, speaking-trumpet, bullhorn, blowhorn, or loudhailer is usually a portable or hand-held, the cone-shaped acoustic horn used to amplify a person's voice or other sounds and direct it in a given direction.

Galton's whistle: A dog whistle is a type of whistle that emits sound in the ultrasonic range, which most humans cannot hear but some other animals can, including dogs and domestic cats, and is used in their training.

Sonar: Sonar is a technique that uses sound propagation to navigate, communicate with or detect objects on or under the surface of the water, such as other vessels.

Stethoscope: The stethoscope is an acoustic medical device for auscultation, or listening to internal sounds of an animal or human body. It typically has a small disc-shaped resonator that is placed against the skin and one or two tubes connected to two earpieces.