The smooth transition of enthusiastic rapid hand clapping into a slow synchronised clapping that follows the completion of a stage entertainment is regarded in western cultures as something of an anticlimax, and gives rise to doubts whether the audience is altogether kindly disposed towards the performers. Synchronised clapping, after all, is a method of showing contempt for a political figure.
In Nature for February 24 a group of physicists from Romania have described an investigation into the mechanism and development of synchronised clapping involving several theatre and opera performances in Romania and Hungary. They found that after a few seconds of incoherent random applause a periodic signal developed in the audience. Synchronisation of the clapping led to a decrease in the average intensity of noise in the room. This was the consequence of a doubling of the clapping period. Since average noise intensity can only be increased by shortening the period again this led to disappearance of the synchronisation and the resumption of uncontrolled clapping.
Once applauding individuals have demonstrated by a high frequency beat they tend to eliminate every alternate beat and end with a synchronised rhythm. Then, in attempting to intensify the applause, the instinct is to relapse into fast clapping, with consequent loss of synchronisation. If members of an audience become aware that halving their clapping rate will bring about synchronisation and diminish the volume of sound they may choose to do so. This happens in smaller and more culturally homogeneous eastern European communities, but is relatively uncommon in western European and North American audiences.