There’s a new buzz on TikTok – well, not a buzz exactly. It’s more of a hum, maybe waves crashing, a purring fan or steady, heavy rain. To me, it sounds like an empty aeroplane, cruising peacefully at altitude. It’s brown noise, a close cousin of the better-known white noise, and TikTok users, particularly the platform’s ADHD community, are all over it: there are 85.3m views for the #brownnoise hashtag.

One top-rated video (1.3m views) shows user @NatalyaBubb trying brown noise. She looks initially startled, then spellbound. “Where did all the thoughts go?” reads the caption over her wide-eyed face. Commenters on her and other brown-noise clips are mainly – though not exclusively – rapturous. “I closed my eyes and literally thought of NOTHING … it makes my brain feel soft in the best way possible”; “This felt like fresh air to my ears”; “Like a soft weighted blanket that I’ve safely swathed my brain in,” says one writer with ADHD.

The “brown” in brown noise is not a colour, but a reference to sound that mimics Brownian motion, the movement pollen makes in water, identified by the botanist Robert Brown in 1827. In essence, brown noise is the familiar, staticky sound of white noise (that is, all the audible frequencies simultaneously) but with the low frequency notes augmented and the less pleasant high frequency notes turned down, counteracting the human ear’s natural tendency to hear higher frequencies louder.

“Brown noise is a more palatable listening experience because most of the higher frequencies, which can be harsh or distracting to the listener, are removed,” says Giles Williams, the music director of commercial music service Rehegoo.

It has fans beyond the ADHD community, including the author Zadie Smith. “I listen to brown noise … day and night,” she told a Penguin podcast. “I live in this denuded soundscape.” My colleague Nikola discovered brown noise at university. “I would only manage to concentrate in coffee shops. When I was poor and couldn’t afford to go to a coffee shop, I tried finding coffee shop sounds on YouTube, and then I found something called ‘brown noise for concentration’. Ever since, I use it every time my mind is all over the place and I need to get work done.”

Several people I speak to use brown noise to drop off at night (“I can’t sleep without it,” says one. “It helps me not wake up suddenly with every tiny noise,” says another.) You can get eight hours’ worth on CBeebies radio and some tinnitus sufferers find it reduces their symptoms. According to Williams, it’s now considered “a viable option for use in deep relaxation rooms or sleep pods” for wellness businesses keen to move away from whale song.

The staticky sound of white noise has been demonstrated to improve sleep and some cognitive tasks for children with ADHD; “white noise” machines have existed since the 1960s. Are there the same proven benefits with brown noise?

Dan Berlau, professor of pharmaceutical sciences at Regis University in Colorado, has reviewed the literature on the benefits of white noise. “I don’t think there’s anything magical about brown noise,” he tells me. “I think all of those sounds can have similar effects on the brain, but people like what brown noise sounds like, so that’s the one that catches on. It sounds like, for this ADHD community on TikTok, they’ve identified brown noise as something that helps them, which is terrific.”

What people actually experience when they listen to brown noise is unclear. Research has not yet investigated the calming, “no thoughts” response to brown noise that the TikTok ADHD community describes. However, “it does make sense,” says Berlau. People with ADHD do not have the regular trickle of “tonic dopamine” of neurotypical brains, he explains, leading to “constant thoughts they can’t really get rid of. Creating this external noise that sort of ‘blankets’ the brain; it makes sense that would calm some of that brain noise. It just hasn’t been confirmed experimentally.”

There are probably other elements at play: the therapeutic effects of full-spectrum noise (whether white, brown or other) have been shown only at high decibel levels, Berlau says. People who find their focus or concentration improves with low-level background brown noise may just be benefiting from “sound masking”: “The sound blocks out other sounds so you’re less distracted.”

This is probably also why people report improved sleep with brown noise. There may be some placebo effect, too. “If a person on TikTok wants to feel the healing power of brown noise, they’ll probably feel it,” says Berlau. Not that he’s unhappy with the craze. “My son has ADHD, we are struggling with a variety of treatments and the more evidence and research on this, the better.”

Brown noise is not for everyone. “There are huge individual differences in the way people’s brains work, so trying to create some sort of one-size-fits-all is unlikely to work,” says Berlau. My friend Helena has ADHD and is ambivalent. “It is completely unsettling to have my thoughts stop after 45 years of cognitive hyperactivity,” she says. “But it does seem to work.”

I do not have ADHD, but on an overloaded week with multiple competing deadlines, travel and a worrying health curveball for my dog, my thoughts are everywhere, all at once. When I test out a range of Spotify and YouTube brown-noise playlists, the effect is mixed: some I hate from the first second, others are bearable as background noise, without particularly improving my concentration. Actually, when I turn to work that requires careful attention, my immediate instinct is to turn it off. My husband, who has tinnitus, finds it aggravates rather than soothes his symptoms.

But if you’re distracted, overstimulated or simply curious, there’s no reason not to have a listen, as Berlau points out. “Unless you’re blasting it to the point where you’re damaging your ears, there’s probably no downside to trying this to see if it helps with your focus.”