Question

Explain why we do not hear echoes in a small room?

Answer 1

1. Sound gets reflected from hard surfaces just like light.
2. Metal surfaces are very good reflectors of sound and reflect the incident sound.
3. The reflected sound is called echo.
4. Two sounds can be distinctly heard when the source and reflector are separated by at least$\frac{1}{10}s$.
5. In$\frac{1}{10}s$, the distance travelled by the sound will be$\frac{1}{10}s\times 330m/s=33m$.
6. So the distance between the source and reflector will be half of $33\mathrm{m}$ i.e.$16.5\mathrm{m}$.
7. So, an echo can be distinctly heard by us only after it has travelled a distance of$16.5\mathrm{m}$.
8. In a small room, the distance travelled is less than$16.5\mathrm{m}$.
9. Therefore, we do not hear echoes in a small room.