Brown Noise for Focus

Distraction by sound is a measurable acoustic effect with a number attached to it. Understanding that number tells you what background noise can realistically do for your concentration — and where brown noise is the wrong choice.

Start By Reframing the Question

People searching for a focus sound are usually hoping for one of two things. The first is that a particular sound will make their brain work better than it does in silence. The second is that a sound will stop the room from taking their attention away.

The evidence for the first is weak to negative in most people. The evidence for the second is solid, quantified, and has an engineering literature behind it. Almost everything useful on this page follows from putting your effort into the second question.

Which means the honest framing is: silence is the baseline, and background noise is a way of buying back part of what an intrusive environment costs you. If you work in a genuinely quiet room, adding noise is unlikely to buy you anything — and might cost you a little. If you work near conversation, it can buy back a measurable amount.

The Number That Predicts How Much Speech Costs You

Room acousticians have been quantifying this for years, because open-plan offices made it an expensive problem. The measure they use is the Speech Transmission Index, or STI — a value from 0 to 1 describing how intelligible speech is at your position. Close to 1 means every word is clear. Below about 0.2 means speech is audible as sound but you can no longer follow it.

The relevant synthesis is Haapakangas, Hongisto and Liebl, The relation between the intelligibility of irrelevant speech and cognitive performance (Indoor Air, 2020), a systematic review of laboratory experiments that manipulated the intelligibility of background speech using wide-band steady-state noise. It pulled together 14 studies reporting 34 tests of the relationship and revised an earlier model from 2005.

The shape of the result is the useful part. Across all tests, performance begins to fall above roughly STI 0.21 and reaches its maximum decrement at about STI 0.44. Above that point it does not get much worse — the damage is already done. For verbal short-term memory tasks, the effect was strongest and most consistent, with performance deteriorating across the range between STI 0.12 and 0.51.

Two implications follow directly. Intelligibility, not loudness, is what hurts. A clearly audible conversation you cannot make out words in costs you far less than a quieter one you can follow. And there is a target rather than a slope. You are not trying to make the room as loud as possible; you are trying to push intelligibility down past the point where the decrement flattens out, and then stop. That is why a modest amount of well-chosen noise can do the whole job.

The review is also careful about what it does not show. Evidence for the relationship in verbal working memory tasks was described as some; for complex verbal tasks, limited. So the strong claim applies to holding verbal material in mind — the kind of thing that breaks when a colleague says your name — and not uniformly to everything you might call "concentrating".

Which Makes Brown Noise the Wrong Colour for Voices

If the goal is to push speech intelligibility down, the masker needs energy where speech intelligibility lives. Consonants — the sounds that carry most of the information in a sentence — sit largely between about 2 and 6 kHz. That is precisely the region brown noise has abandoned.

Brown noise falls at close to 6 decibels per octave, measured on this site's generator at −5.98 dB per octave. By 1 kHz it has already dropped about 20 dB relative to 100 Hz, and by 5 kHz about 34 dB, so there is very little of it left up there. Set loud enough to cover the murmur underneath a conversation, it will still leave the consonants standing clear on top — so the words remain followable, STI stays high, and the cost to your verbal memory stays where it was. You will have made the room louder without making it less distracting.

For speech, the colours that carry treble are the ones that work: white noise is flat and by a distance the most effective speech masker of the five, and green noise concentrates its energy in the mid-frequencies where the voice itself sits, which makes it the most efficient choice per unit of volume and the one that survives a laptop speaker.

So what is brown noise good for in a working day? Everything below speech. Traffic, an HVAC unit, a lift motor, a neighbour's bass, footsteps and door slams above you, roadworks, the low roar of a café. Those are low-frequency intrusions and brown noise handles them at a lower volume than any other colour here can manage. It is also the colour that fades most completely into ambience, which is worth something in a sound you intend to run for hours.

The useful mental model: brown noise for rumble, white or green for voices. If your open-plan office has both, that is a real argument for pink as a compromise or for layering — and it is why a page that only sold you brown noise would be doing you a disservice.

There Is No Evidence of a Cognitive Boost — and Some Against

The claim to be sceptical of is the one where noise does something to your brain that makes it work better. On the current evidence, that appears to be true for a specific group and untrue, or mildly counterproductive, for everyone else.

The 2024 meta-analysis in the Journal of the American Academy of Child and Adolescent Psychiatry pooled randomised trials of white and pink noise on laboratory attention tasks. Among comparison participants without ADHD — eleven studies, 335 people — the pooled effect was negative: broadband noise made performance slightly worse rather than better, and the authors flag the possible detrimental effect as needing further study. Among participants with ADHD or high ADHD symptoms it was a small positive effect, which is covered on the ADHD page.

Read that carefully, because it is easy to over-correct. Those experiments were run in quiet laboratories, where the noise had nothing to mask. They isolate the direct effect of noise on cognition with the masking benefit removed — and that direct effect, in people without ADHD, is not in your favour.

Which is the whole argument of this page in one line: in a quiet room, background noise is a small cost; in a noisy one, it is a way of removing a larger cost. If you already work somewhere silent and you are hoping noise will sharpen you up, the evidence says do not bother. If you are trying to make a noisy environment survivable, you are on solid ground.

There is nothing here about brainwaves, entrainment or frequencies that unlock focus states. No sound on this site does any of that, and no page on this site will claim it does.

A Setup That Holds Up Over a Full Working Day

Match the colour to the intrusion, not to the mood. Spend thirty seconds identifying what is actually breaking your concentration. Voices, or rumble? That single question determines the colour, and getting it right means you need far less volume.

Aim to blur, not to erase. The target is the point where you can hear that people are talking but can no longer follow what they are saying. That is where the intelligibility curve flattens. Past it you are adding exposure for no return.

Set it before you start and do not touch it again. A volume slider you keep revisiting has become another thing competing for your attention. Choose the level during the first minute, then leave it alone for the session.

Prefer a speaker to headphones where you can. Headphones raise total exposure for the same perceived level and are the harder habit to keep modest over an eight-hour day. Where headphones are the only option — shared desk, café — a level you could still hold a conversation over is the practical ceiling. No safe long-duration level has been established for this use, so err low.

Use it to mark the session, not to fill the day. Many people find the strongest benefit is the start signal: noise on means work has begun. That effect costs nothing and does not require the sound to run for six hours.

Studying, Reading and Writing Are Not the Same Task

"Focus" covers activities that respond very differently to sound, and the review discussed above gives a reason why: the intelligibility effect was strongest and most consistent for verbal short-term memory, while evidence for complex verbal tasks was limited.

Memorising, note-taking, mental arithmetic, proofreading. These lean hardest on holding verbal material in mind, and they are the tasks most reliably damaged by intelligible speech nearby. This is where masking earns the most.

Reading for comprehension and writing. Intuitively the most vulnerable, but the evidence base for complex verbal tasks is thinner rather than stronger, so treat any confident claim here with suspicion — including a confident claim that noise will help. Try it and judge for yourself.

Repetitive or procedural work. Data entry, admin, tidying files, routine code changes. These are the least sensitive to background sound of any kind, and if you find noise helps here it is probably doing something motivational rather than cognitive. That is a legitimate reason to use it; it is just not the reason the studies describe.

One warning that applies across all of them: music with lyrics is not a masker. It is speech you have chosen, and speech is the thing doing the damage. If you want the room quieter in the sense that matters, a broadband sound with no words in it is a categorically different tool from a playlist.

The Web Player, and What the App Adds for Work

The player above generates brown noise in the browser — nothing to download, nothing recorded, so no loop that starts announcing itself midway through the afternoon. Free web sessions run for 30 minutes, which is about one focused block and enough to find out whether the approach suits you.

For work the constraint that bites is different from the sleep case: you want the sound to survive a whole day, tab switches, a closed laptop lid and a walk to a meeting. The free Android app removes the 30-minute cap, keeps playing in the background with the screen off, needs no connection once installed, and carries all five colours — which matters here because the honest advice on this page is that the right colour depends on whether your problem is voices or rumble, and you should be able to switch between them in a second rather than reading another article about it.

Frequently Asked Questions

Related pages

• Brown Noise for Sleep — The free web player, plus the full guide to brown noise for sleep, focus, and tinnitus.
• Brown Noise — The deepest colour, measured at −5.98 dB per octave — best for traffic rumble and long overnight sessions.
• White Noise — The flat reference colour, measured at 0.00 dB per octave — the best of the five at making speech unintelligible.
• Green Noise — The mid-frequency colour — a pink base with a broad 500 Hz emphasis, and the only one of the five with no standard definition.
• Brown Noise for ADHD — The 2024 meta-analysis with its real numbers — a small benefit on lab attention tasks in ADHD, a negative effect without it, and zero studies of brown noise.
• Brown Noise for Tinnitus — Masking versus habituation, why the pitch of your tinnitus decides the colour, and where sound therapy actually sits in the 2014 clinical guideline.
• Brown Noise App — Which brown noise app to install, whether it is really free, and the five things an installed app does that a browser tab is not allowed to.