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Car Ride Sound for Baby Sleep

Many babies who fight sleep at home drift off a few minutes into a drive. Part of that is the sound: a deep, steady engine hum and road rumble that never stops. This is that sound, so you can skip the 2 a.m. loop around the block.

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About this sound

Sound	Deep engine and road rumble with a soft tyre hiss
Pitch	Mostly low frequencies, like the inside of a quiet car
Movement	A gentle slow sway in volume, like a smooth highway
Length	10 hours, seamless loop
Screen	Picture for a few seconds, then fades to fully black
Made by	Generated and mixed in-house by Shush Bean (not a recording)

What the research says

Why the car is so sleepy

Inside a car, a baby gets steady low sound plus gentle motion. Before birth, babies heard mainly low sounds, because the mother’s body muffles high pitches by 40 to 50 dB ^[1]. A deep, constant rumble is close to that familiar sound world. Steady broadband sound also masks sudden noises: with white noise, 80% of newborns fell asleep within five minutes, compared with 25% without it ^[2].

The sound, not the car seat

The American Academy of Pediatrics advises that car seats and other sitting devices are not for routine sleep outside the car. If your baby falls asleep in the car seat, move them to a firm, flat crib or bassinet, on their back, when you arrive ^[3]. This video lets you use the car sound in the right place.

What we still don’t know

There are no studies of car-sound recordings in babies, and the sound alone cannot copy the motion of a drive. Pair it with rocking or holding if your baby needs movement to settle.

Why we fade to a dark screen

Young children’s body clocks are very sensitive to light in the evening. In a small study of preschoolers (ages 3–5), one hour of bright evening light cut the sleep hormone melatonin by 88%, and it stayed low for at least 50 minutes after the light was switched off ^[4]. A phone screen is far dimmer than that study’s light, and babies were not studied, but the lesson is simple: the less light in the nursery, the better. That is why every Shush Bean video shows its picture only briefly and then fades to a fully black screen.

How loud is too loud

Researchers in Toronto measured 14 infant sleep machines at full volume. At 30 cm (about 1 foot) every one of them was louder than 50 dBA, the limit recommended for hospital nurseries, and three could exceed 85 dBA ^[5]. Their advice: keep the device well away from the crib, keep the volume low, and do not run it at full volume all night. The American Academy of Pediatrics’ safe sleep guidance still comes first: baby on their back, on a firm flat surface, in their own crib or bassinet with nothing else in it ^[3].

How to use it

Hold or rock your baby while it plays if they usually need motion to fall asleep.
Once asleep, lay baby on their back in their crib; car seats are for the car.
Keep the volume low: the rumble should sit in the background.

Use sound gently

Keep it low. Choose the lowest volume that still masks background noise. If you have to raise your voice to talk over it, it is too loud.
Keep it far. Put the phone or speaker across the room, not in or next to the crib. Researchers who measured infant sleep machines advised keeping them more than 2 metres (about 6.5 feet) away.
Keep sleep safe. Baby on their back, in their own crib or bassinet, with nothing else in it.

Source: Hugh et al., Pediatrics (2014), as summarized by Children's Hospital of Philadelphia.

Questions

Is this a real car recording?

No. We build the engine hum and road sound ourselves so there are no horns, indicators or sudden noises.

Why is it so deep?

Low sounds are soothing and mask household noise well. We keep high, sharp pitches out completely.

Can I use it for naps?

Yes. It works the same for day naps; just keep it quiet and stop it when baby wakes.

References

Gerhardt KJ, Abrams RM. Fetal exposures to sound and vibroacoustic stimulation. Journal of Perinatology. 2000;20(S1):S21–S30. Link
Spencer JA, Moran DJ, Lee A, Talbert D. White noise and sleep induction. Archives of Disease in Childhood. 1990;65(1):135–137. Link
Moon RY, Carlin RF, Hand I; AAP Task Force on Sudden Infant Death Syndrome. Sleep-related infant deaths: updated 2022 recommendations for reducing infant deaths in the sleep environment. Pediatrics. 2022;150(1):e2022057990. Link
Akacem LD, Wright KP, LeBourgeois MK. Sensitivity of the circadian system to evening bright light in preschool-age children. Physiological Reports. 2018;6(5):e13617. Link
Hugh SC, Wolter NE, Propst EJ, Gordon KA, Cushing SL, Papsin BC. Infant sleep machines and hazardous sound pressure levels. Pediatrics. 2014;133(4):677–681. Link

This page summarizes published research for general information. It is not medical advice. Research on sleep sounds for babies is still limited; talk to your pediatrician about your baby’s sleep and crying.