Short answer
The three noise colours are defined by how energy is distributed across the frequency spectrum: white noise has equal power at every frequency (sounds like TV static or a fan), pink noise decreases by 3 dB per octave making lower tones more prominent (sounds like steady rain), and brown noise decreases by 6 dB per octave producing a deep, bass-heavy rumble (like ocean waves or distant thunder) — these are technical signal definitions, not just marketing labels. All three can mask environmental sounds, and personal texture preference is the dominant factor in real-world use. One important nuance: a 2023 study in Frontiers in Human Neuroscience found continuous overnight pink noise reduced REM sleep by roughly 18–19 minutes per night compared to silence, so it is not as straightforwardly beneficial for sleep as it is often marketed.
Sereno helps with this on your iPhone and works on device for privacy — a pay-once app with no subscription. Test it on a real example and check the current App Store listing for details.
What to look for before choosing
- White noise: flat spectrum, equal energy per hertz — broadest frequency masking, sounds like hiss or static
- Pink noise: −3 dB/octave, more bass-forward and natural-sounding (rain, rustling leaves) — the most common spectral shape in natural environments
- Brown noise: −6 dB/octave, deep low-frequency rumble (ocean, waterfall, distant thunder) — the 'warmest' sounding of the three
- All three mask environmental sound; which you prefer is largely a matter of individual texture preference
- Recent research cautions that continuous overnight pink noise may reduce REM sleep — a timer and moderate volume apply especially here
A practical decision process
- White noise: flat spectrum, equal energy per hertz — broadest frequency masking, sounds like hiss or static.
- Pink noise: −3 dB/octave, more bass-forward and natural-sounding (rain, rustling leaves) — the most common spectral shape in natural environments.
- Brown noise: −6 dB/octave, deep low-frequency rumble (ocean, waterfall, distant thunder) — the 'warmest' sounding of the three.
- All three mask environmental sound; which you prefer is largely a matter of individual texture preference.
- Recent research cautions that continuous overnight pink noise may reduce REM sleep — a timer and moderate volume apply especially here.
Quick comparison
| Need | What to check | Why it matters |
|---|---|---|
| Pricing model | Check whether useful features require a subscription, a one-time unlock, or neither. | The cheapest app on day one may not be cheapest after a year. |
| Privacy model | Prefer on-device work when the content is sensitive. | Private documents, resumes, study data, and family content deserve careful handling. |
| Export / lock-in | Confirm file formats, sharing, backup, and deletion controls. | A good app should help you finish the task, not trap your work. |
Where Sereno fits
Sereno is a strong fit when you want a focused, private, pay-once tool for this.
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This page is an independent buying guide. App Store features and prices can change, so confirm details on the listing before purchase.