The Lullasure reference shelf
Infant sound
reference sheets.
Three references to save, print or share with another caregiver. Each keeps the source and its limits beside the practical takeaway.
The full text is available below in HTML. The PDFs are printable companions; the HTML versions provide the accessible reading format.
01 / Source map
Where did 50 dBA come from?
A hospital reference has a setting, a metric and a date. Keep all three attached.
Here are three verifiable checkpoints in nursery-noise literature. This is a selected source map, not a claim to identify the first-ever use of the number.
- 1999
Hospital nursery criteria
For occupied, newly built or renovated hospital nurseries, Philbin and colleagues recommended an hourly average (Leq) no higher than 50 dBA. This concerned the overall sound environment, not a home machine setting.
Philbin, Robertson & Hall (1999) - 2006
The metric changes the meaning
The 2006 NICU standards set limits of 45 dBA for hourly Leq and 50 dBA for hourly L10. L10 and Leq describe different aspects of sound; the number alone is incomplete.
Philbin & Evans (2006) - 2014
A device-study comparison
The infant sleep-machine paper used 50 dBA as a hospital-nursery comparison. It did not establish a universal home safety limit.
Hugh and colleagues (2014)
Before using a number, ask three questions
- For which setting and population?
- Which metric and averaging period?
- What can the measurement actually establish?
A hospital design criterion is not a guarantee about a baby's home exposure. A live phone estimate is not an hourly average or a hearing assessment.
02 / Study card
What the 80% statistic meant
Keep the denominator, age and outcome beside the percentage.
White noise
16 / 2080%
fell asleep within five minutes
Control
5 / 2025%
fell asleep within five minutes
A result about settling
This small trial described a particular group and a short observation. It is not an 80% promise for your baby or for a modern app.
Questions this statistic cannot settle
- How long should a machine run?
- What happens with repeated overnight use?
- What sound level suits a particular home setup?
Spencer, Moran, Lee & Talbert (1990), White noise and sleep induction. Original indexed abstract checked; this card does not reproduce unverified equipment settings or follow-up details.
Read the full study explanation03 / Printable checklist
Compare a nursery sound setup
A short record for comparing placements and settings, with the measurement limits kept visible.
Use this with the crib empty. A phone check describes sound at the measuring phone; it cannot assess a baby's hearing or certify a nursery.
Identify the sound, speaker and volume controls you intend to use.
Keep the sound source in its intended position, away from the baby and with cords out of reach.
Position the measuring phone near the baby's usual head position at mattress height; keep its microphone clear.
Keep the phone still. Record whether the app shows a live estimate or a named average, plus the observation period.
Change one setting or placement and repeat under comparable conditions.
Remove the phone before the baby uses the crib. Decide when the added sound will stop.
Keep these details together
| Date / room | Space for your notes on the printable checklist |
|---|---|
| Speaker / sound | Space for your notes on the printable checklist |
| Volume control(s) | Space for your notes on the printable checklist |
| Speaker and phone positions | Space for your notes on the printable checklist |
| Phone / app / validation status | Space for your notes on the printable checklist |
| Metric / observation duration | Space for your notes on the printable checklist |
| First observation / interruptions | Space for your notes on the printable checklist |
| Change made / second observation | Space for your notes on the printable checklist |
| Planned stop / timer | Space for your notes on the printable checklist |
Keep the limits with the number
Lullasure currently displays live estimates and guidance bands without completed device calibration. These are unvalidated. Watching a live value for 30 seconds does not turn it into a 30-second average.
NIOSH documents measurement metrics and calibration; NIH describes an infant sleep space clear of extra objects. The comparison workflow is Lullasure's editorial planning aid, not a clinical protocol.