why can we hear echo's in long galleries and big hall

1.	why can we hear echo's in long galleries and big hall
Answer» To hear an echo clearly, the time interval between the original sound and the echo must be at least 0.1 s. Since the speed of sound in air is 344 m/s, the distance travelled by sound in 0.I s = 344 m/s x 0.1 s = 34.4 m. So to hear an echo clearly, the minimum distance of the reflecting surface should be half this distance that is 17.2 m. Because the distance between us and the obstacle should be 17.2m for hearing the echo.In small rooms there is no 17.2m distance. So we cant hear any echo.Whereas in a big hall there is 17.2m distance. So we can hear many echo.

Answer»

To hear an echo clearly, the time interval between the original sound and the echo must be at least 0.1 s.

Since the speed of sound in air is 344 m/s, the distance travelled by sound in 0.I s = 344 m/s x 0.1 s = 34.4 m.

So to hear an echo clearly, the minimum distance of the reflecting surface should be half this distance that is 17.2 m.

Because the distance between us and the obstacle should be 17.2m for hearing the echo.In small rooms there is no 17.2m distance. So we cant hear any echo.Whereas in a big hall there is 17.2m distance. So we can hear many echo.

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