Question

"the recommended audience strength of churches should be two-third to get the optimum reverberation " Justify the above statement

Answer 1

When the surfaces of an indoor place are hard and smooth, very small energy is lost at each impact of sound and many reflections take place before the sound dies down. This repeated reflection of sound is known as reverberation or prolongation. Then, if sound exists too long, then successive words of a speech will overlap and confuse. The remedy for this defect is to select a correct time of reverberation known as optimum time of reverberation. This is achieved by suitably selecting a proper absorbent or acoustic materials for different reflecting surfaces.The walls are covered with porous substances like compressed fibre board, rough plaster or draperies. The regular motions of air mlecules which constitute the sound waves, are converted into irregular motions in the pores of such materials and consequently less sound energy is deflected.

Hence, it is very important to have optimum time of reverberation for better hearing aids in the room.

The indicated target audience strength is based on many factors like the acoustic material use, their absorption coefficients. If the audience is exceeded than the recommended value, the sound absorption may exceed and the room will give a dead sound which is not expected for a cultural heritage place like church. Also, in churches, various types of acoustic measurements are done using source-reciever placement combinations, dome position, symmetry of the room etc for the purpose of deciding the target audience strength. Hence, it is of utmost importance.