Class 9 Physics Sound Reverberation

Reverberation : Multiple Reflections

In a big hall, where there a musical concerts/dance shows etc, there will be repeated reflections from walls all round. The sound will persist for a very long time due to this multiple reflections. The repeated reflection that results in this persistence of sound is called reverberation.

In a big hall, reverberation is required so that the entire hall can hear the sound. At the same time, if the reverberation is very high, the sound will persist for too long even if the source of sound has actually stopped. So, this is undesirable. The reverberation effect should be controlled. Several acoustic techniques are deployed to do this.

Uses of Multiple Reflection

  • Some musical instruments have a tube followed by a conical opening. This architecture helps to reflect sound again and again such that most of the sound waves move in the forward direction. Eg: Horn, Trumpets, Loud speakers etc

  • Stethoscope is used by a doctor to hear the patient's heart beat. The sound from the heart reaches the ear of the doctor by multiple reflections as shown.


  • The walls and ceiling of concert halls are curved because of which sound after reflection reaches all corners of the hall. Also, roof and walls and seats of the auditorium are generally covered with sound-absorbent materials like compressed fireboard, rough plaster and draperies for a pronounced sound effect

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