Question

Which of the following will not produce echo?

• A. Mirror
• B. Rock
• C. Marble
• D. Porous materials

Hint:

Porous materials absorb sound waves and are effective in preventing echoes, making them ideal for acoustically sensitive environments.

Answer 1

The Correct Option is D

An echo is a reflection of sound that arrives at the listener after a delay. For an echo to occur, the surface must be hard and smooth to reflect sound waves effectively.
Porous materials, such as fabric, foam, and certain types of wood, absorb sound waves rather than reflect them, thus preventing echoes from forming.
On the other hand, hard surfaces like mirrors, rocks, and marble reflect sound, which can lead to the creation of an echo.