Why the ‘Tock’ of a Pickleball Is So Annoying

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Its relatively high pitch and sudden start-and-stop combine to grate on the human ear. Redesigning paddles could help.

By Eugenia Cheng – WSJ

As the weather improves I’m happy to be playing tennis again. However, one of the tennis courts in my local park was turned into two pickleball courts, and I’ve joined the apparently large number of people who find the sound of pickleball annoying. I want to try to be rational despite my disappointment at losing a court, so I decided to look into the math of the pickleball sound.

Pickleball paddles are small and hard, and the balls are plastic with holes in them, whereas tennis rackets have vibrating strings, and the balls are made of felt-coated rubber and filled with air. So where tennis makes a pleasant ringing sound, pickleball makes a sharp high-pitched “tock.” The difference is in the waveform of the sound—specifically its amplitude, frequency, and shape.

Mathematically, the amplitude is a measure of how far apart the peaks and troughs of the wave are; we humans hear this as loudness. The frequency is a measure of how fast the oscillations repeat; we hear this as pitch. But the shape of the wave interests me the most because that’s what we hear as timbre, or the quality of the sound.

The purest form of sound has a sine curve, oscillating smoothly and symmetrically up and down. A close approximation of this regular shape, though not an exact one, can be produced by carefully engineered mechanisms, but most sounds have waves that are more jagged and asymmetrical, built by adding waves together that represent a combination of frequencies. Adding a higher frequency to a lower one adds more small ups and downs between the main peaks and troughs. The more we add higher frequencies, the more the shape of the wave changes, and with it the timbre of the sound.

Those higher-frequency sounds contributing to the overall wave are called overtones. Classically trained singers learn how to produce more of certain overtones to make their voice richer and more audible over an orchestra without electronic amplification.

Not all overtones are to everyone’s taste, in music or pickleball. Pickleball sounds aren’t louder or particularly higher overall than other sounds of balls being struck, but they have some high-pitched frequencies that crucially contribute to the timbre. The sounds have been analyzed to have a spike in overtone frequencies around 1000 Hertz, about two octaves above middle C, toward the top end of a soprano range. Those frequencies don’t carry further across the air, but human ears are more sensitive to them so we hear them more clearly at a distance and, perhaps, find them more aggravating.

Some experts are trying to design rackets that eliminate those frequencies. A similar issue has been at play for golf clubs. In 2007, Nike introduced a new driver that gave golfers superior control, but it was unpopular because golfers didn’t like its sound, which was quantified by analyzing its spectrum of frequencies. There’s much more money in golf than pickleball so the technology is more advanced for engineering good golf clubs that also sound right.

There are other ways to analyze the wave formed by hitting a pickleball. For example, the sound starts and finishes sharply, without much ringing resonance. This probably has to do with the plastic used for the ball, which has much less give than a tennis ball, and also the holes, which are designed to reduce the ball’s susceptibility to being blown off course by the wind. However, it seems that the official regulations on the design of a pickleball are more constraining than those on the paddle, so there is more scope for redesigning the paddle than the ball.

Math can’t help me like the sound of pickleball more, but analyzing what is bothering me can help me become less wound up by it.

Corrections & Amplifications
An electronic oscillator can produce largely single-frequency tones free of overtones, which can closely approximate a smooth, symmetrical sine wave when measured. An earlier version of this article suggested that a true sine wave can only be produced digitally, but there are imperfections in digitally produced sounds as well.