Question

what is echo and reverberation. how can it be read used

Answer 1

$ECHO$ --

If we shout or clap near a suitable reflecting object like large wall or a big building or a hill, we shall hear the same sound again after a short interval of time. This is called $Echo$ and it is on account of reflection of sound from the reflecting surface.

Thus, Echo is the repetition of a sound due to reflection of original sound from a suitable reflecting surface (obstacle).

> CONDITION OF PRODUCTION OF DISTINCT ECHO --

The sensation of a particular sound persists in our brain for about 0.1 s. This is known as the persistence of hearing. If another sound reaches our ear within the time, then our brain will be able to analyse the second sound distinctly. Due to this reason, the time interval between the original sound and the reflected sound must be at least 0.1 s or more.

$REVERBERATION$ --

When a sound is produced in a big hall (or auditorium), the sound waves suffer multiple reflections from the walls, ceiling and floor of the hall. As a result, multiple echoes should be formed. However, the time of echoes is so short that these are not heard distinctly but all echoes overlap with the original sound. As a result, the original sound persists for some time until the sound energy is reduced to a value where it is no longer audible. This persistence of sound for some time due to repeated reflection is called REVERBERATION.

Thus, Reverberation of sound is the phenomenon of persistence of a sound in a big hall due to repeated reflections from the walls, ceiling and floor of the hall.

>> Excessive Reverberation in a hall or auditorium can be controlled by using the following steps :

1. Panels made of sound absorbing materials like compressed fibreboard or felt are fitted on the walls and ceiling of the hall. The penals absorb most of incident sounds and thus minimise Reverberation.

2. The walls of halls should have a rough plaster so that they may absorb sound.

3. Heavy curtains are put on doors and windows of the hall. They absorb sound and reduce Reverberation.

4. Carpets are put on the floor to absorb sound and reduce Reverberation.

5. The seats arranged in the hall should be cushioned seats so as to absorb sound.

Answer 2

the repetition of sound caused by the reflection of sound wave is called an echo