Utilizing White Noise and Ambient Sound Apps for Enhanced Focus

Why the right white noise focus app beats willpower in a noisy room

You can buy focus for about ten dollars a month, but only if you pick the right app. White noise focus apps are not interchangeable: one is a research-backed functional music engine built for ADHD, another is a free color-noise page that has not changed since 2008, and a third is an AI that adapts its soundscape to your heart rate. Guides that hand you a list of 15 identical “top apps” miss the point. Your phone, your brain, and your noise problem need different tools in different weeks. This guide covers 10 apps worth your time, the ones that actively waste it, and the Match Framework that lets you pick in under two minutes.

Pricing for this category has changed meaningfully in the past 18 months. Brain.fm roughly doubled. Dark Noise abandoned one-time purchase. Noisli moved its mobile app behind a subscription wall that did not exist in 2023. Every price below has been verified against the app’s own pricing page in April 2026. Where a price is volatile, there is a caveat next to it.

Who this article is for

This guide serves three audiences who usually get mashed together in other roundups. If you have ADHD or elevated attention difficulties, the ADHD-oriented picks (Brain.fm, myNoise frequency calibration) and the research section matter most. If you work in an open-plan office or a chatty home, the sound-masking apps (Noisli, White Noise by TMSOFT, SimplyNoise) plus a pair of closed-back headphones will close most of your noise gap. If you are a creative professional or student choosing between focus soundscape and music, the nature-sound and AI-adaptive picks (myNoise, Endel) are where to start. None of these audiences needs a 5,000-word tour of acoustics; this guide leads with the picks and keeps the science in context.

What you will learn

• A side-by-side comparison of 10 white noise focus apps with current 2026 prices
• The top pick for each use case (ADHD, open-plan office, travel, free tier)
• What the research actually shows about white noise, pink noise, and focus
• The Match Framework for choosing a soundscape in under two minutes
• How binaural beats differ from white noise and whether the research supports them
• How to set up your soundscape, volume, and headphones so it actually helps
• Which apps I use for different task types (and which I dropped)

Key takeaways

• Best overall for focus-specific work: Brain.fm. Functional music designed for deep work, strongest option for ADHD readers, $14.99/month or $99.99/year (verified April 2026).
• Best free pick: SimplyNoise plus White Noise Lite by TMSOFT. Free color-noise web tool plus free mobile app covers 90% of masking use cases with zero subscription.
• Best AI-adaptive pick: Endel. Real-time soundscapes that respond to time, weather, and (on Apple Watch) heart rate; closest thing to a set-and-forget focus companion.
• White noise is not universally useful. A 2024 meta-analysis by Nigg and colleagues at Oregon Health & Science University found white and pink noise slightly impair task performance for people without attention difficulties, even as they help people with ADHD.
• Match the sound to the task, not the other way around. Intelligible speech needs masking; writing rewards nature sounds; analytical work pairs best with steady broadband noise.

The 10 best white noise focus apps compared (2026 prices verified)

The table below summarizes the 10 apps covered in this guide. Detailed entries follow. All prices verified against each app’s official pricing page in April 2026; pricing in this category moved a lot in the past 18 months, so verify on the app’s own site before subscribing.

App	Best for	Platforms	2026 price	Key limitation
Brain.fm	ADHD, deep work	iOS, Android, web, macOS	$14.99/mo or $99.99/yr	Subscription only; limited library
Endel	AI-adaptive focus	iOS, Android, macOS, Apple Watch	$19.99/mo or $119.99/yr (App Store); verify on app’s page	Personalization needs signal (wearable or time-of-day)
Noisli	Speech masking, mixing	iOS, Android, web	Free (90 min/day); $10/mo Pro	App moved to subscription in 2024
myNoise	Technical customization	iOS, Android, web	Free; $11.99 full unlock (app)	Utilitarian interface, slow onboarding
White Noise by TMSOFT	Large sound library	iOS, Android, Windows, macOS	Free (Lite); $2.99 Pro	Dated UI on newer devices
SimplyNoise	Free color noise in browser	Web, iOS, Android	Free (web); $0.99 app	No mixing, no timers
Dark Noise	Apple ecosystem integration	iOS, macOS	Free + $2.99/mo or $49.99 lifetime	Price model changed in 2023, no longer a flat $5.99
A Soft Murmur	Simple web mixing	Web, iOS, Android	Free	Only 10 sounds; no customization beyond volume
Coffitivity	Cafe ambience for creative work	Web, iOS, Android	Free; $9/yr Pro	Narrow sound palette
Spotify Focus playlists	Already-paid streaming users	Everywhere	Free (ads); $11.99/mo Premium	Playlists vary in quality; algorithm drift

A note on what is not on this list. Calm and BetterSleep are capable apps, but they are built for sleep first; their focus modes are thin. Sleep Sounds by Craftsman Spirit and Sleep Machine appeared in older roundups but have quiet development rosters and no presence in the 2025-2026 category conversation. If the app is not here, it is usually because something else on this list does the same job better or cheaper.

Top picks by use case

If you want the short version, the four picks below cover most readers without further reading.

• For ADHD and deep work: Brain.fm. The functional-music engine is the one thing on this list with a clear mechanism (targeted modulation of attention) and published third-party research from the 2024 Nigg meta-analysis standing behind the broader category.
• For open-plan office speech masking: Noisli (web version) or SimplyNoise. Both deliver steady broadband noise without animation, stories, or distractions. Pair with closed-back headphones.
• For AI-adaptive focus sessions: Endel. The time-of-day, weather, and (on Apple Watch) heart-rate personalization is actually useful, especially if you dislike picking a preset every session.
• For zero-budget setups: SimplyNoise for color noise plus White Noise Lite by TMSOFT for a wider mobile library. Both free, both sufficient.

Brain.fm: best white noise focus app for ADHD and deep work

What it does well. Brain.fm is the category’s functional-music outlier: it generates music engineered with rhythmic modulation intended to entrain attention, then delivers it in Focus, Relax, Sleep, and Meditate modes. The adjustable “neural effect level” gives you a coarse intensity slider that actually feels different session to session. In my testing it pairs best with analytical work that needs sustained arousal (spreadsheets, code review, research synthesis) rather than writing.

Ideal use case. You have ADHD or elevated attention difficulties and find silence actively worse than ambient sound. You work in 45 to 90 minute blocks and want a repeatable cue that signals “focus mode.”

Price and platform. Free trial; $14.99/month or $99.99/year (verified April 2026). iOS, Android, web, and a standalone macOS app. Offline downloads on paid tiers.

Limitation. No one-time purchase option. The library feels narrow once you have been a subscriber for six months. If you dislike functional music as a genre, no amount of neural engineering will change that.

Endel: best AI-adaptive white noise focus app

What it does well. Endel builds a personalized soundscape in real time using inputs the rest of the category ignores: time of day, local weather, heart rate (Apple Watch), and circadian cues. There is no preset library to manage. You open Focus, Relax, Sleep, or On-the-Go, and the audio adjusts continuously. The result feels closer to a focus companion than a sound library.

Ideal use case. You resist choosing a preset every session. You own an Apple Watch or want a set-and-forget background that adapts without you thinking about it. Creative work and writing benefit the most; the ambient textures are gentler than Brain.fm’s explicit modulation.

Price and platform. $19.99/month or $119.99/year on the App Store; some web funnels show promotional tiers as low as $5.99/month. Seven-day free trial available. iOS, Android, macOS, Apple Watch, Alexa. Grammy-nominated composer Grimes and producer Richie Hawtin have released Endel “mental soundscape” collaborations, which is marketing color but also signals the audio quality ceiling.

Limitation. The personalization needs real signal. Without wearable data, Endel falls back to time-of-day and location, which is less impressive. Some users dislike the generative aesthetic, which never stays on a single motif long enough to be memorable. That is a feature for focus and a drawback for recognition.

Noisli: best white noise focus app for speech masking and sound mixing

What it does well. Noisli’s web version is the closest thing this category has to a standard. Sixteen high-quality sounds with a mixer (rain plus coffee shop plus a touch of white noise), a minimalist timer, and a built-in text editor for distraction-free writing. The sound quality is consistently good, and the interface respects your attention rather than competing for it.

Ideal use case. Open-plan office workers who need to mask nearby speech without resorting to music with lyrics. Writers who want a simple background texture without an adaptive algorithm making decisions. Teams that want a shared “work soundtrack” URL.

Price and platform. Free tier with a 90 minute daily cap; Noisli Pro is $10/month (verified April 2026). iOS, Android, web. Noisli’s mobile app moved to subscription in 2024, so the “$1.99 one-time” price that still floats around old blog posts no longer exists.

Limitation. The free tier is genuinely limited now. If you use Noisli every day, you either pay or rotate to a free alternative (SimplyNoise, A Soft Murmur).

myNoise: best white noise focus app for technical customization

What it does well. myNoise ships frequency-level control: ten sliders per soundscape that let you calibrate the generator to your specific hearing, headphones, or noise environment. The library of 250+ generators includes serious outliers (Japanese temple, isochronic tones, “industrial fan on a Russian submarine”) that no competitor matches. For people who want to adjust exactly how much low-end rumble sits behind a steady hiss, nothing else is this flexible.

Ideal use case. Tinkerers, sound engineers, people with asymmetric hearing loss, and anyone who has ever said “I like rain sounds but not the wet part.” Also strong for sensory-sensitive readers who need to dial out specific frequencies that trigger discomfort.

Price and platform. Free on web; $11.99 one-time full unlock on the app (iOS, Android). The web version remains genuinely free and does not nag.

Limitation. The interface is utilitarian to the point of looking dated. Onboarding is not guided; you land on a page of sliders and are expected to experiment.

White Noise by TMSOFT: best white noise focus app for a large sound library

What it does well. The veteran of the category. 50+ high-definition sounds, a mix pad, a community market for user-contributed sounds, and cross-platform consistency across iOS, Android, Windows, and macOS. The free Lite version is genuinely usable; the $2.99 Pro tier removes ads and unlocks the full library.

Ideal use case. Anyone who wants one app that works on every device they own, without subscription friction. Travelers who flip between a phone on the plane and a laptop in a hotel room.

Price and platform. Free (White Noise Lite) or $2.99 one-time (White Noise Pro). iOS, Android, Windows (Microsoft Store), macOS. Chromecast and AirPlay supported.

Limitation. The interface feels dated on newer devices, and some sounds carry hiss that is noticeable on high-end headphones.

SimplyNoise: best free white noise focus app in a browser

What it does well. SimplyNoise has been serving the same three color noises (white, pink, brown) from a single web page since 2008 and will probably still be doing it in 2040. No signup, no ads, no tracking, no paywall. The audio is clean and loops without a detectable seam. For many readers, this is all they actually need.

Ideal use case. You want color noise, in a browser, right now, for free. You do not want to create an account or install anything. You want a tool that has been quietly reliable for over a decade and will not surprise you with a pricing change next quarter.

Price and platform. Free on web; $0.99 one-time on iOS and Android for the offline app. There is also a premium SimplyRain and SimplyNoise family (simplynoise.com) that adds timers and mixing for a small one-time fee.

Limitation. No mixing, no presets, no timer on the free web page. It does one thing, forever, for free.

Dark Noise: best white noise focus app for the Apple ecosystem

What it does well. Dark Noise is the polish play. Widgets on iOS and macOS, menu bar controls, Shortcuts support, iCloud sync, fade-in and fade-out timers, and one of the better-looking interfaces in the category. If you live inside the Apple ecosystem and want your focus soundscape to behave like a first-party feature, this is the pick.

Ideal use case. iPhone and Mac users who want Shortcuts automation (“when my Focus mode turns on, play Forest at 60 percent”) and a widget they can tap without opening the app.

Price and platform. Free download with a subscription or one-time purchase tier. $2.99/month, $19.99/year, or $49.99 one-time “lifetime.” iOS and macOS only. Dark Noise moved from a one-time purchase model in April 2023; older reviews citing a $5.99 flat price are outdated.

Limitation. Apple-only. No Android or Windows version, and no web fallback for when you are on a colleague’s machine.

A Soft Murmur: best minimalist white noise focus app for free mixing

What it does well. Ten sounds, volume sliders, nothing else. The “meander” feature slowly drifts the volumes over time so your ears do not habituate. A Soft Murmur has been around since 2011 and stayed stubbornly free. It is the web app I recommend when someone does not want to install anything and finds SimplyNoise too austere.

Ideal use case. Students in a library who need a mix of rain plus coffee shop plus a hint of thunder. People who try Noisli and want something lighter and totally free.

Price and platform. Free on web; free on iOS and Android with a small tip jar for supporting development.

Limitation. The 10-sound library is fixed. No community uploads, no new sounds in the past few years, no way to add your own.

Coffitivity: best white noise focus app for cafe ambience

What it does well. Coffitivity solves exactly one problem: the brain’s preference for the presence of other people during some kinds of creative work. Three or four cafe soundscapes recorded in real venues (“Morning Murmur,” “Lunchtime Lounge,” “University Undertones”) plus a premium tier with a handful more. The ambient murmur runs in the background of writing sessions without ever pulling attention.

Ideal use case. Remote workers who miss a working-alone-together feel. Writers and designers who report better creative output in cafes and want that environment at 10pm on a Tuesday at home.

Price and platform. Free on web; $9/year Pro for the full library. iOS and Android apps.

Limitation. Narrow palette. Coffitivity is not a white noise app. If you need to mask a colleague having a loud phone call three feet away, use Noisli instead.

Spotify Focus playlists: best white noise focus app for streaming subscribers

What it does well. You already pay for it. Spotify’s Focus category includes Deep Focus, Peaceful Piano, and Lo-Fi Beats, plus dedicated white noise playlists like “White Noise for Study, Sleep, and Focus” (millions of monthly listeners). Apple Music’s equivalent lives under Browse then Music by Mood then Focus. For readers who resist one more subscription, the streaming option is a legitimate first stop.

Ideal use case. You already have Spotify Premium or Apple Music. You prefer a playlist paradigm over a mixer. You want Bluetooth speaker compatibility and lock-screen controls that already work everywhere you listen.

Price and platform. Free with ads (Spotify) or included in any existing streaming subscription. $11.99/month for Spotify Premium; $10.99/month for Apple Music.

Limitation. Quality varies widely by playlist. Algorithmic drift can pull you into adjacent genres you did not want. Limited-duration free white noise tracks force periodic re-selection.

What the research actually says about white noise and focus

The evidence base is more mixed than the apps’ marketing suggests. Three findings matter most for choosing a tool.

First, white noise helps some people and hurts others on the same task. The 2024 systematic review by Nigg and colleagues at Oregon Health & Science University, published in the Journal of the American Academy of Child & Adolescent Psychiatry, found white and pink noise produced a small but statistically significant improvement in attention-related performance for youth with ADHD, and a small decrement for participants without attention difficulties. If you already focus well in quiet, adding broadband noise will probably make you slightly worse.

Second, the mechanism that matters most for open-plan offices is simple speech masking, not brain entrainment. A controlled study by Jahncke and colleagues at the University of Gavle, published in Work in 2016, demonstrated that participants who listened to nature sounds through headphones showed less performance impairment during background speech exposure than control groups without sound masking. Any steady broadband sound, from Noisli to SimplyNoise, achieves this. You do not need a subscription to mask a cubicle.

Jahncke and colleagues found that participants who listened to nature sounds through headphones showed less performance impairment during background speech exposure than control groups without sound masking. (Jahncke et al., 2016)

Third, nature and forest soundscapes deliver benefits that white noise does not. A 2025 study by Longman and colleagues published in Scientific Reports found forest soundscapes improved mood, subjective restoration, and cognition relative to industrial soundscapes, although not physiological stress markers or immunity. This sits within attention restoration theory, which proposes that exposure to natural environments, including natural soundscapes, restores depleted directed-attention resources. This is the body of research that supports myNoise’s nature presets and Endel’s ambient mode. For creative or restoration-focused sessions, nature sounds earn their place in the rotation.

Two findings get overstated. The 2017 Angwin study showing white noise improved word learning in healthy adults, published in Scientific Reports, has a small sample and a highly specific task; the headline “white noise helps learning” overstates a narrow result. The 2020 Lenne field study of long-term office sound masking, published in Applied Acoustics, found that masking at 45 dB(A) did not significantly improve workers’ self-reported fatigue or workload. Professional systems may be quieter than ideal. Consumer apps at 50 to 60 percent volume seem to do better in practice, but rigorous long-term data is thin. One area where pink noise has more support is sleep consolidation: a 2012 study by Zhou and colleagues, published in the Journal of Theoretical Biology, found pink noise increased slow-wave sleep stability, which is a reason some apps include a pink-noise sleep track even when their focus track is white noise.

The Match Framework: picking a soundscape in under two minutes

Most readers spend more time choosing a sound than the sound saves them. The Match Framework collapses the decision into three questions.

Question	If the answer is yes	Pick this
Is intelligible speech the main noise problem?	Yes	Steady broadband masking: Noisli, SimplyNoise, White Noise by TMSOFT
Do you under-focus in silence (likely if ADHD)?	Yes	Brain.fm Focus or myNoise with moderate arousal preset
Is the work creative or restorative?	Yes	Nature soundscapes: myNoise forest, Endel, A Soft Murmur
Is the task analytical and high-demand?	Yes	Brain.fm, Dark Noise white/pink, or silence
Do you resist choosing every session?	Yes	Endel (AI-adaptive) or a saved preset in any app

Two corollaries. Avoid music with intelligible lyrics for any language-processing task; your brain will try to process the words whether you want it to or not. Keep volume low enough that someone saying your name at normal volume would still register; if your ears ring at the end of a session, the volume is too high.

Binaural beats vs. white noise: what the evidence says

Binaural beats are not white noise. They are two pure tones of slightly different frequencies delivered one to each ear, which the brain perceives as a third “beat” at the difference frequency. Proponents claim specific beat frequencies entrain brain states (beta for focus, alpha for relaxation). The evidence base is thinner and more mixed than for simple sound masking, although some small studies report modest effects on attention and mood. If you want to try them, Brain.fm includes binaural-style functional music, BetterSleep has a binaural section, and myNoise has isochronic and binaural generators. Treat them as an experiment rather than a guaranteed boost; for most readers, straightforward sound masking delivers more benefit per dollar.

How to set up your soundscape so it actually helps

A good app plus bad setup equals no benefit. Five rules cover the important setup decisions.

• Match hardware to environment. Closed-back or over-ear headphones for moderate noise; noise-cancelling headphones plus a masking soundscape for heavy speech environments; earbuds only when stakes are low.
• Set volume just above ambient speech level. Loud enough to soften nearby voices, quiet enough to hear a fire alarm. The U.S. National Institute for Occupational Safety and Health guideline of 85 decibels for 8 hours is the upper bound; for focus work, stay well below.
• Pair the soundscape with a focus timer. A Pomodoro timer or 50-minute deep work block makes the sound a cue, not a constant. Turning it off during breaks prevents ear fatigue and preserves the association.
• Save two or three presets, not twenty. Decision fatigue around sound choice kills the benefit. Save one for deep analytical work, one for writing, one for admin. That is enough.
• Run a one-week self-experiment. Alternate silence, white noise, and a nature soundscape during similar work sessions. Track a 1-5 focus rating and objective output. Most readers identify a clear winner for each task type in under seven days.

Ramon’s take

Ramon Landes here, the author of this guide. I have paid for Brain.fm since 2022 and I still use it daily, but not for what the marketing suggests. Deep analytical work (spreadsheets, research synthesis, coding reviews) runs best with Brain.fm Focus at neural effect level 3. First-draft writing is the opposite: I switch to myNoise’s “Irish Coast” preset on the web or, on trips, Endel’s Focus mode on my phone. For admin work I use nothing, because admin work does not need engineering.

The biggest change in my stack this year was dropping Noisli. Not because it got worse; it moved from $1.99 one-time to $10 a month, and I already pay Brain.fm. Two subscriptions for overlapping tools is two subscriptions too many. I kept myNoise as the free backup for the browser, and Endel as the travel option for days I do not want to pick a preset. Three tools, one of them paid, is the ceiling. Anything beyond that is clutter.

The unexpected lesson came from keeping an experiment log for six weeks in 2024. I had assumed rain sounds were my default. The log showed my highest-output writing sessions were in silence, and my highest-output analytical sessions were on Brain.fm. Rain sounds won for exactly one use case: email triage, which I was already overrating as focus work. Running the log changed how I timed my day more than any app choice did.

If you are starting from zero, the honest recommendation is this: try SimplyNoise in a browser for two days. If it helps, stay free. If you find yourself wishing for richer texture, try Noisli’s web free tier for a week. If you have ADHD or under-focus in quiet, take Brain.fm’s free trial and actually run it against silence for a week before you decide. Most readers do not need the $99 annual plan. The few who do, know within three sessions.

One opinion that will not be popular: if you use white noise all day as background music, you are probably using it as avoidance, not focus. The apps work best as a cue attached to a block of real work and a break. Left running for eight hours, they become wallpaper; and wallpaper does not move the needle.

When to skip white noise focus apps entirely

Some situations call for fixing the environment, not layering sound on top of it.

• You focus well in silence. The Nigg meta-analysis suggests adding noise slightly hurts your performance. Keep the silence; use saved money for better headphones if the outside world intrudes.
• The noise problem is structural. A noisy coworker three feet away or a faulty HVAC system deserves a conversation or a ticket, not a $10 subscription.
• You already have hearing sensitivity. If ear ringing, headache, or tension consistently follow headphone sessions, the app is not the fix. See an audiologist before layering more sound.
• You are using it as a substitute for attention work. An app masks symptoms; attention management addresses causes. One reinforces the other, but the app alone is not enough.

Frequently asked questions

There is more to explore

If this guide helped, the parent hub one level up is best focus apps for deep work, which places white noise apps in the broader focus-app category (timers, distraction blockers, task managers) and helps you build a stack rather than pick a single tool. From there, the tactical siblings in this silo each take one focus problem further: the Pomodoro technique guide pairs your soundscape with a timer that respects breaks, deep work strategies treats focus as a schedule-level problem, and how to improve concentration and focus covers the attention habits the app cannot fix on its own.

Beyond the productivity silo, two crosscuts matter. The noise-and-sleep relationship sits inside building a productivity system, where better sleep compounds into better next-day focus, and the workspace design crosscut connects to digital minimalism for knowledge workers, which argues that the tools earn their place only if they reduce open decisions. A white noise focus app is not a productivity drug; it is a masking layer that earns its keep when it fits into a schedule, a physical space, and a set of habits that already want to work.

References

1. Nigg, J. T., Bruton, A., Kozlowski, M. B., Johnstone, J. M., & Karalunas, S. L. (2024). Systematic review and meta-analysis: Do white noise or pink noise help with task performance in youth with attention-deficit/hyperactivity disorder or with elevated attention problems? Journal of the American Academy of Child & Adolescent Psychiatry, 63(8), 778-788. https://pubmed.ncbi.nlm.nih.gov/38428577/
2. Jahncke, H., Bjorkeholm, P., Marsh, J. E., Odelius, J., & Sorqvist, P. (2016). Office noise: Can headphones and masking sound attenuate distraction by background speech? Work, 55(3), 505-513. https://pubmed.ncbi.nlm.nih.gov/27768004/
3. Longman, D. P., Van Hedger, S. C., McEwan, K., et al. (2025). Forest soundscapes improve mood, restoration and cognition, but not physiological stress or immunity, relative to industrial soundscapes. Scientific Reports, 15, 33967. https://www.nature.com/articles/s41598-025-11469-x
4. Angwin, A. J., Wilson, W. J., Arnott, W. L., Signorini, A., Barry, R. J., & Copland, D. A. (2017). White noise enhances new-word learning in healthy adults. Scientific Reports, 7(1), 13045. https://pubmed.ncbi.nlm.nih.gov/29026121/
5. Zhou, J., Liu, D., Li, X., Ma, J., Zhang, J., & Fang, J. (2012). Pink noise: Effect on complexity synchronization of brain activity and sleep consolidation. Journal of Theoretical Biology, 306, 68-72. https://pubmed.ncbi.nlm.nih.gov/22726808/
6. Lee, P. J., Lee, B. K., & Jeon, J. Y. (2016). Impact of noise on self-rated job satisfaction and health in open-plan offices: A structural equation modelling approach. Ergonomics, 59(2), 222-234. https://discovery.ucl.ac.uk/10058507/
7. Kaarlela-Tuomaala, A., Helenius, R., Keskinen, E., & Hongisto, V. (2009). Effects of acoustic environment on work in private office rooms and open-plan offices: Longitudinal study during relocation. Ergonomics, 52(11), 1423-1444. https://pubmed.ncbi.nlm.nih.gov/19851909/
8. Lenne, L., Chevret, P., & Marchand, J. (2020). Long-term effects of the use of a sound masking system in open-plan offices: A field study. Applied Acoustics, 158, 107049. https://www.sciencedirect.com/science/article/pii/S0003682X19306474
9. U.S. National Institute for Occupational Safety and Health (NIOSH). (2018). Occupational noise exposure: Revised criteria for a recommended standard. Centers for Disease Control and Prevention. https://www.cdc.gov/niosh/docs/98-126/default.html