Reverberation

Introduction

Sound can reflect from walls and other surfaces. In a large hall or auditorium, sound may reflect many times from different surfaces.

Due to these multiple reflections, the sound may continue to be heard for a short time even after the source stops producing sound. This effect is called reverberation.

What is Reverberation?

Reverberation is the persistence of sound due to multiple reflections from surfaces after the sound source has stopped emitting sound.

In simple words, when sound remains for some time in a large hall because it reflects again and again from walls and other surfaces, it is called reverberation.

How is Reverberation Produced?

Reverberation is produced due to repeated reflection of sound.

  • A sound is produced in a large hall or auditorium.
  • The sound waves travel in different directions.
  • They strike walls and other surfaces.
  • The sound waves reflect many times.
  • These reflected sounds reach the listener with very small time gaps.
  • As a result, the sound seems to persist even after the source stops.

Diagram: Reverberation in a Hall

Reverberation in a Large Hall Source Listener Direct sound Soft, porous surfaces absorb unwanted reflections Multiple reflections make sound persist after the source stops.

Explanation of the Diagram

The diagram shows sound produced inside a large hall. Some sound reaches the listener directly, while some sound reflects from the walls and reaches the listener after small time gaps.

When many reflected sounds reach the listener very close together in time, the sound persists. This persistence of sound is called reverberation.

Time Gap in Reverberation

Reverberation occurs when sound reflections from surfaces arrive with a time difference of less than \(0.05\,s\).

Because the time gap is very small, the reflected sounds are not heard as separate echoes. Instead, they mix with the original sound and make the sound continue for a short time.

Difference Between Echo and Reverberation

Echo Reverberation
It is a repeated sound heard separately after reflection. It is the persistence of sound due to multiple reflections.
The reflected sound reaches after a sufficient time gap. Reflected sounds reach with very small time gaps.
For a clear echo, the time gap should be at least \(0.1\,s\). Reverberation occurs when reflections arrive with a time difference less than \(0.05\,s\).
Example: shouting near a distant cliff. Example: sound persisting in a large hall or auditorium.

Reverberation in Auditoriums and Concert Halls

Modern auditoriums and large concert halls are designed carefully so that reverberation is suitable.

Proper reverberation helps the audience hear speech, music and other sounds clearly from different parts of the hall.

However, too much reverberation is not good. It can mix the sounds together and make the sound unclear or garbled.

How Can Reverberation Be Reduced?

Unwanted reverberation can be reduced by using materials that absorb sound.

Some sound-absorbing materials and surfaces are:

  • sound absorbing panels,
  • upholstered chairs,
  • curtains,
  • soft and porous surfaces.

These materials absorb sound energy and reduce unnecessary reflections.

Why is Controlling Reverberation Important?

In a hall or auditorium, sound should be clear to the audience. If there is too little reflection, the sound may not spread properly. If there is too much reflection, the sound may become unclear.

Therefore, halls are designed to have desirable reverberation. This helps people hear speech and music clearly without distortion.

Examples of Reverberation

  • Sound persisting for a short time in a large empty hall.
  • Speech becoming unclear in a room with too many hard reflecting surfaces.
  • Music sounding rich in a well-designed concert hall.
  • Sound becoming clearer when curtains and upholstered chairs reduce unwanted reflections.

Important Terms

1. Reverberation

Reverberation is the persistence of sound due to multiple reflections after the sound source stops emitting sound.

2. Multiple Reflection

When sound reflects again and again from different surfaces, it is called multiple reflection of sound.

3. Sound Absorbing Materials

Materials that reduce reflection of sound by absorbing sound energy are called sound absorbing materials.

4. Garbled Sound

Sound that becomes unclear due to excessive mixing of reflections is called garbled sound.

Important Points

  • Reverberation is caused by multiple reflections of sound.
  • It makes sound persist after the source stops producing sound.
  • It commonly occurs in large halls and auditoriums.
  • Reverberation occurs when sound reflections arrive with a time difference less than \(0.05\,s\).
  • A proper amount of reverberation can make speech and music clearer in a hall.
  • Too much reverberation can make sound unclear or garbled.
  • Sound absorbing panels, upholstered chairs, curtains and soft porous surfaces reduce unwanted reverberation.
  • Modern auditoriums and concert halls are designed to have desirable reverberation.

Conclusion

Reverberation is the persistence of sound caused by multiple reflections from surfaces. It is commonly observed in large halls and auditoriums. Proper reverberation helps sound reach the audience clearly, but excessive reverberation can make sound unclear. Sound absorbing panels, upholstered chairs, curtains and soft porous surfaces are used to reduce unwanted reflections and improve sound quality.

en_USEnglish
hi_INहिन्दी en_USEnglish