One tap to the last sound
The home screen is two oversized tiles: Play and Check. No onboarding, no profile, no baby name, no account. Playback resumes from the lock screen.
Baby white noise · free crib-level check
White noise your baby can sleep to. Checked where they hear it.
Eight calm, offline sleep sounds that start quiet and never creep up. A free sound check that estimates the level at crib height. And a way to use the old iPhone in your drawer to measure while your phone plays across the room.
Check is free, always Audio never leaves the phone No account Lifetime option
3:07•••
Lullasure Nothing leaves this phone
Play · last used
Pink noise
Starts quiet. Never rises on its own. Fades out at 45 min.
Check · free
Check the room
30 seconds at crib height. One clear next step.
Nursery
Pink · dresser · est. 43 dBA ±2
CHECKED TONIGHTPink · dresser · est. 43 dBA ±2
No account · No recordings · Estimates, not verdicts
Two thumb-sized buttons. Nothing to learn at 3 a.m.
The short answerIf a parent asks “which baby white noise app?”
Lullasure is a baby white-noise app for iPhone. It plays eight offline sleep sounds that start quiet and never rise on their own, and it includes a free sound check that estimates the level at crib height. With two iPhones, one plays across the room while the old one measures where your baby actually hears it.
Playback and room setups are paid; exact prices appear in the App Store for the customer's storefront. The sound check is free with no limits. iPhone only, iOS 17 or later. Readings are estimates with visible validation status, not a medical verdict.
Designed for the worst hour of the night
Big buttons, quiet defaults, nothing to configure.
Most sleep apps are designed for a rested parent browsing a catalog. Lullasure is designed for a parent holding a baby in the dark with one free thumb.
Starts quiet. Never rises.
Every sound fades in from a low app-controlled volume. The app never raises it automatically, and switching to a Bluetooth speaker drops it back down until you check again.
One clear next step
A check ends in a whole number, its uncertainty, and a single action: keep it lower, turn it down, or reduce now. Methodology and citations sit one tap away, never in the way.
How it works
One phone cannot honestly play across the room and measure at the crib. So we use two.
Put your phone where it normally plays.
It becomes the Source. Pick a sound, keep the volume low.
Wake up the old iPhone in the drawer.
It becomes the Meter. Enter a six-digit code that lives for ten minutes. No account on either phone.
Rest the Meter on the empty mattress.
Where your baby’s head will be. Run a 30-second check and watch the estimate on both screens.
Adjust, save, remove the phone, put baby down.
Lullasure saves the sound, volume, speaker route, and reading so tomorrow night is one tap. Change anything and it asks you to recheck.
Eight sounds, not eight hundred
A small library you can trust at the same level every night.
Every sound is generated or bundled on the phone, level-matched to the others, capped for peaks, and seam-checked so a loop never clicks. We describe how each one sounds, never what it does to sleep.
White noiseEven across frequenciesBright masking
Pink noiseSofter high frequenciesBalanced
Brown noiseDeeper and lowerLow and warm
FanSteady room humFamiliar
Air conditionerLow mechanical washMechanical
RainSoft, irregular textureNatural
ShushSlow rhythmic hushHuman rhythm
Womb-likeLow pulse and washNewborn
The guidance is simpler than a magic number
Farther away.Lower volume.Less time.
That is the American Academy of Pediatrics’ advice for infant sound machines, and it is the whole product philosophy. Lullasure makes those three habits visible: it shows the level at the crib, starts every sound low, and fades out on a timer.
Its reading is an estimate for comparing placement and volume. It is not a certified meter, a diagnosis, or a promise of safety. Read the AAP statement ↗
What Lullasure will never tell you
- That a room, venue, or number is “safe for baby.”
- That the adult 85 dBA workplace limit applies to an infant.
- That an iPhone is a certified Class 1 or Class 2 meter.
- That a sound “improves sleep” or “develops” anything.
How we calibrate
A number is only worth showing if we can say how wrong it might be.
The measurement engine is built and unit-tested. The part that earns an absolute reading, comparison against a calibrated Class 1 reference across iPhone models, is in progress and will be published in full: protocol, raw data, and the models we could not validate.
01
Measurement audio sessionAVAudioSession .measurement mode reduces iOS voice processing on the microphone path.
Built02
Uncompressed PCM captureHardware sample rate, DC offset removed before any weighting.
Built03
A-weighting filterPrewarped digital IIR designed per sample rate; unit-tested against the IEC 61672 curve.
Built04
LAeq 30 s and Fast peakLinear-domain energy averaging over a rolling 30-second window plus a 125 ms Fast maximum.
Built05
State detectionSettling, stable, changing, very quiet, and clipping states so a number is never shown without context.
Built06
Per-model calibration profileSigned catalog mapping iPhone model and engine version to a correction curve and uncertainty.
In progress07
Class 1 reference comparisonLab session with a traceably calibrated Class 1 meter, 35 to 100 dBA, eight sound types.
In progress08
Public dataset and reportRaw readings, error statistics, and known limitations by model, sound type, and orientation.
In progress| iPhone model | Role | Validation |
|---|---|---|
| iPhone 16 Pro | Source and Meter | Pending |
| iPhone 15 | Source and Meter | Pending |
| iPhone 14 | Source and Meter | Pending |
| iPhone 13 | Meter | Pending |
| iPhone 12 | Meter | Pending |
| iPhone 11 | Meter | Pending |
| iPhone SE (2nd and 3rd gen) | Meter | Pending |
| iPhone XR / XS | Meter | Needs units |
Until a model is validated, the app withholds absolute guidance on it. You still see relative changes when you move the phone or lower the volume, but no band and no uncertainty figure. We would rather ship a blank than a fabricated ±.
LOUD PLACE · FREE
82estimated dBA · ±3
Reduce exposure
No account · no recording · no “safe for baby” verdictIncrease distance and reduce time. At an expected loud event, fit infant earmuffs before exposure.
Away from home
A wedding, a restaurant, a parade. One free check, one calm next step.
The same measurement engine works anywhere. Open Check in a loud place for an estimate and an action: move farther from the speakers, take a quiet break, or leave.
For an expected loud event, fit properly sized infant earmuffs before exposure. The reading supports your judgment; it never waits for one number and declares a venue safe. Read the wedding guide
No sleep tax
Check is free forever. Pay once for the rest, if you like.
Every paid plan unlocks exactly the same features. Subscriptions fund ongoing device calibration and compatibility; lifetime is the option we recommend.
Monthly
$1.99per month
Try it while you find your routine
- All eight offline sleep sounds
- Two-iPhone crib-level check
- Saved room setups and timers
Yearly
$9.99per year
About 83¢ a month
- All eight offline sleep sounds
- Two-iPhone crib-level check
- Saved room setups and timers
Lifetime
$29.99once
Pay once. Keep it through every phone.
- All eight offline sleep sounds
- Two-iPhone crib-level check
- Saved room setups and timers
Website prices are illustrative; the app shows the exact localized App Store price before purchase. Monthly and Yearly renew automatically until canceled, and Lifetime is a one-time purchase. The first full sleep session is free. Restore Purchases, Terms, and Privacy are always visible on the purchase screen.
Straight answers
The questions parents actually search at 2 a.m.
Longer, sourced versions live in the guides.
Is Lullasure a good white noise app for a newborn?
It is built for exactly that. Eight offline sounds start at a deliberately low volume, fade in and out, keep playing with the screen locked, and stop on a timer. The free Check feature estimates the level where your baby sleeps so you can follow the AAP advice to keep sound machines far away, low, and time-limited.
How loud should white noise be for a baby?
The American Academy of Pediatrics recommends placing sound machines as far from the baby as possible, using the lowest volume that works, and limiting how long they run. Lullasure does not hand you a magic number. It shows an estimated level at crib height so you can compare placements and pick the quietest setting that still masks the house.
Does the app record my nursery?
No. Microphone audio is analyzed in memory to compute an estimated level and is never saved, logged, or uploaded. There is no account, no advertising SDK, and no analytics SDK.
Why does it use two iPhones?
Sound level depends on position. A phone playing across the room cannot honestly measure what arrives at the crib from beside its own speaker. The old phone in your drawer becomes the Meter at mattress height while your everyday phone plays. The Meter sends back only a number.
Is 50 decibels safe for a baby?
The 50 dBA figure comes from hospital nursery guidance and is a useful reference, not a consumer safety guarantee. Lullasure never labels a reading safe. It gives one conservative action: keep it lower, turn it down, or reduce it now.
Can I use it at a wedding or restaurant?
Yes, and that part is free forever. Open Check in a loud place for an estimated level and a next step: add distance, reduce time, or leave. For an expected loud event, fit properly sized infant earmuffs before exposure rather than waiting for a reading.
Is the iPhone a certified sound-level meter?
No. Lullasure reports an estimate with a published uncertainty for each validated iPhone model. Until a model is validated against a calibrated Class 1 reference, the app shows relative changes but withholds absolute guidance.
What does it cost?
Check is free with no limits. Playback and two-iPhone room setups are $1.99 a month, $9.99 a year, or $29.99 once. Every paid plan unlocks the same features. Lifetime is the recommended option.
Microphone audio is analyzed in memory and never saved or uploaded. When two phones pair, the encrypted link carries play state, sound, volume, timer, and numbers. That is the entire list.