A sound machine for a baby should be set no louder than 50 decibels, which is roughly the volume of a quiet conversation or a running shower heard from another room. For context, sounds at or below 70 decibels are unlikely to cause hearing loss even after prolonged exposure, but babies sleep with sound machines for hours at a time, and their ear canals are smaller, which can amplify sound. Keeping the volume well below that 70-decibel ceiling gives your baby a comfortable margin of safety.
Why Volume Matters More for Babies
Repeated or prolonged exposure to sounds at or above 85 decibels can cause noise-induced hearing loss in anyone, and the louder the sound, the faster damage occurs. Babies face additional risk because they can’t tell you something is too loud, and a sound machine typically runs for the entire duration of a nap or overnight sleep, meaning exposure time is measured in hours rather than minutes.
Beyond hearing damage, there’s growing evidence that continuous moderate-intensity white noise can affect early development. A 2024 scoping review published in Sleep Medicine found that extended noise exposure during sleep may harm auditory and cognitive development, with animal studies showing clear negative effects and human data pointing in the same direction. The concern isn’t about using a sound machine at all. It’s about running one too loud or for too long without breaks.
How to Check the Volume
Most people can’t reliably guess decibel levels by ear, so a free sound meter app on your phone is the easiest way to check. Place your phone where your baby’s head rests in the crib and measure the reading with the sound machine running at its normal position. You’re aiming for around 50 decibels at the baby’s ear, not at the machine itself. A machine set to a moderate level on a nightstand might register much louder if it’s right next to the crib rail.
If you don’t have an app handy, a simple test: stand at the crib and speak in a normal conversational voice. The sound machine should be quieter than your speaking voice, not competing with it.
Placement Makes a Big Difference
Where you put the machine matters as much as the volume dial. The recommendation is to place it at least 7 feet away from your child’s crib. Sound intensity drops significantly with distance, so a machine across the room can be set to a slightly higher output and still register at a safe level by the time it reaches your baby’s ears. A machine clipped to the crib rail, on the other hand, delivers its full volume directly into the sleep space, and even a “low” setting might be too loud at that range.
Portable sound machines designed to attach to strollers or car seats are convenient, but they’re often placed inches from a baby’s head. If you use one, keep the volume at its lowest setting and limit the duration.
White, Pink, and Brown Noise
Sound machines offer different types of noise, and the best choice depends on your baby’s preference. White noise is the classic steady “shhh,” similar to a fan or radio static. It’s particularly good at masking sudden sounds like a door closing or a dog barking because it covers all frequencies at equal intensity.
Pink noise emphasizes lower frequencies, producing a softer, deeper sound like rainfall or wind through trees. Some research suggests pink noise promotes more stable, deeper sleep. Brown noise goes even deeper, with a rumbling quality like a waterfall, and can work well for children who seem bothered by higher-pitched sounds.
There’s no single correct choice. Nationwide Children’s Hospital recommends trying different types and observing which helps your child settle best. The volume and placement guidelines are the same regardless of which color noise you use.
How Long to Run It
Many parents leave a sound machine running all night, but limiting continuous use is worth considering given the developmental concerns around extended noise exposure during sleep. Some machines have auto-shutoff timers that turn the sound off after 30, 45, or 60 minutes, which is typically enough time for a baby to fall into deeper sleep. If your baby wakes when the machine clicks off, running it continuously at a low volume is a reasonable compromise, but avoid the habit of cranking it up louder to keep them asleep through disruptions.
As your child gets older, gradually weaning off the sound machine helps them learn to sleep through normal household noise on their own. There’s no hard deadline for this, but most sleep consultants suggest starting the transition sometime between 1 and 2 years of age.
Quick Reference
- Target volume: around 50 decibels at the crib, never exceeding 70
- Minimum distance: 7 feet from the crib
- Duration: use a timer when possible, or keep volume at the lowest effective setting for overnight use
- Verification: use a free decibel meter app at the baby’s head position to confirm the actual level