The results: The hand configuration that produced the loudest clap—85.2 dB—consisted of holding the hands 45 degrees to each other with the palms partially overlapping.

The research, published in the journal Physical Review Research, shows that the characteristic “pop” sound of a clap is not just from two hands smashing into each other but a much more complex ...

The study revealed that the tone of a clap depends heavily on hand shape and cavity size (as expected). Cupped hands trap more air, producing a lower, deeper pop. Flat palms create higher frequencies.

Understanding the physics of hand clapping, Fu says, could help develop methods to identify people by their claps — for example, allowing users to log into a device based on their unique clap.

It starts with a single neighbor clapping. Soon dozens more join in, throwing open their front doors or hanging from their windows to put their hands together and say “wooooo.” ...

The study, published in the journal Physical Review Research, shows that the sound of a clap is not just due to two hands smashing into each other.