Question

Why echoes can't be heard clearly in a small room?

• A. Because small rooms absorb more sound.
• B. Beacuse time gap between direct sound and reflected sound too low to be perceptible by human ear.
• C. Because small rooms reflect less amount of energy.
• D. Because the minimum distance required to hear an echo in a small room is less than 17.2 m

Answer 1

Answer: (B), (D)

The correct options are

(B) Because the time gap between direct sound and reflected sound is too low to be perceptible by the human ear.

(D) Because the minimum distance required to hear an echo in a small room is less than 17.2 m

1. For an echo to be heard distinctly, the time interval between the original sound and the reflected one must be at least 0.1 seconds.
2. This happens when the distance between the obstacle and the source is more than 17.2 m.
3. In small rooms, reflected sound comes back before 0.1 seconds as the distance between the source and the obstacle is less than 17.2 m.
4. So, we are not able to hear echoes distinctly in small rooms.