Imagine you have just made a tough basketball shot and your friend comes over to give you a celebratory high five. Now imagine that high five was the most perfect high five with the most perfect sound, you know the one. So satisfying right? but what is that sound exactly? It is the same sound you hear when you clap your hands.
While both flat and domed handclaps disturb the air and create pressure waves that our ears detect as sounds, they do so in slightly different ways. As two flat hands collide, the air between them is forced out increasingly quickly, ultimately exceeding the speed of sound. This creates an abrupt pressure change, resulting in shock waves that make up a large part of the noise we hear. With cupped palms, meanwhile, there is usually a gap left around the thumbs, so not all the air is expelled. This makes for slightly gentler pressure changes that do not create much of a shock wave, but which produce what’s known as a Helmholtz resonance.
Of course everyone claps in different ways, “The loudest configuration, generating an average sound pressure of 85.2 dB, is one in which the hands are held at about 45 degrees to one another and the palms partially overlap… On the other hand decibels aren’t everything when it comes to sound: the frequency distribution is vital too. So what works best there? Turns out there is one mode of clapping that produces particularly low tones. This involves keeping the hands at 45 degrees, but with the palms fully overlapped and slightly domed to enclose a pocket of air” (Hiscott 2023). No matter which way you clap or give a high five. Two hands are the perfect form of your own musical percussion instrument that is also free!
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