Tag: acoustics

Rooms having walls less than 17.2 m away from each other, no echo can be heard. here, 159 m is greater than 17.2 m. So an echo will be heard if other conditions are fulfilled.

If the time interval between original sound and reflected sound is more than $\frac{1}{10}\,s$, then the original sound and the reflected sound can be clearly heard. This reflected sound is known as echo.

Time, after which an echo is heard is given by $t = \dfrac {Distance}{Speed \ \ of \ \ sound \ \ in \ \ air}$
Therefore, since speed of sound in air increases with the increase in temperature, so the time after which echo will be heard decreases. Hence, echo will be heard, sooner than the echo heard when temperature near $44^0C$

In rooms having walls less than 17.2m away from each other, no echo can be heard.

For the production of an echo, the reflecting surface or the obstacle should be rigid such as building, hill, cliff. Echo can be produced if the size of the obstacle reflecting the sound is quite large.

In rooms having walls less than 17.2m away from each other, no echo can be heard. Here,walls of the room are at a distance of 159 m, much greater than 17.2m. So an echo will be heard if other conditions are fulfilled.

The minimum distance in air between the observer and the obstacle for an echo to be heard clearly is nearly 17.2m. This condition is followed here but for the production of an echo, the obstacle should be rigid.

For the production of an echo, the reflecting surface or the obstacle should be rigid such as building, hill, cliff etc.

Minimum frequency to the human ear is 20
$\therefore T= \dfrac {1} {F}$
$T=\dfrac{1} {20}$
$d= V \times t$
$d= V\times \dfrac {1} {20}$
$\therefore$ The minimum distance is$ \dfrac {V} {20}$, where V is speed of the sound.

The echo of the first signal will overlap with the second signal. Thus, an echo will not be absent