Womb sounds for baby sleep

What this sound is

The womb sound is not one sound but a few layers added together. At the bottom sits a continuous low-frequency hum close to brown noise, resembling the bed of blood flow and gut sounds inside the body. On top rides a steady pulse: the mother's heartbeat as it reaches the baby, muffled. There are almost no highs, because the abdominal wall, amniotic fluid and tissue filter high frequencies out; that is how a baby hears the outside world, muffled and soft. The womb sound in Agubu carries that muffled, bass-heavy character and plays for as long as you need. The card in the app describes it as the world as heard from inside, most familiar to newborns.

Why it may help

The core idea is simple: the womb was not a quiet place. Before birth your baby lived inside a continuous low rumble; the quiet room after birth is new and empty. Because the womb sound is the closest imitation of that environment, it may settle some babies quickly, especially in the first weeks. Like white noise it also masks sudden household sounds. On the evidence, studies that look at womb sounds specifically are small and few, and the evidence for steady sounds in general is weak and mixed. We cannot say it works for every baby. In the early months it is easy to try and safe at a low level; let Agubu's sleep log decide.

Safe use

Because it is bass-heavy it never sounds harsh even when loud, which makes it easy to raise the level without noticing. The rules are the ones in the white noise guide.

• Keep the volume low: the level recommended for hospital nurseries is about 50 decibels. The practical test is simple: if you can talk in a normal voice in the room and still be heard easily, the level is fine; if the sound drowns you out, it is too loud.
• Do not put the phone or speaker in the cot or on its edge. Keep it at least one to two metres away, and avoid headphones, sound toys attached to the cot and any speaker close to the baby's ear.
• Use the timer. Fading the sound out 20 to 30 minutes after your baby has fallen asleep is usually enough. If you leave it on through the night, keep the level genuinely low.
• Turn it down once your baby has settled, and do not let a loud setting become the habit even briefly. Do not leave it running all day while your baby is awake, because it masks the speech they learn from.
• If the womb sound has become part of every sleep and you want to reduce the dependency as your baby grows, lower the volume gradually over a few nights rather than stopping at once.

How to play it in Agubu

1. Open Agubu, go to the Sounds tab at the bottom and tap the Womb sound card under Womb. This sound is in the free tier; there is no account to create and nothing to download, it plays on your device offline.
2. Set the volume with your own ears first: if you can speak in a normal voice in the room and still be heard, it is low enough. Place the phone one to two metres from the cot.
3. Tap Timer and pick a duration. When it runs out the sound does not stop abruptly; it fades down slowly. Twenty to thirty minutes after your baby has fallen asleep is enough on most nights.
4. If you like, layer it in the Mixer: a quiet shushing layer over the womb sound resembles being soothed in someone's arms. The Mixer is a Premium feature and blends up to four sounds at separate levels. Sounds play without ads and the app needs no internet connection.

When to use it

• In the newborn weeks, right after coming home from hospital, at every settle to sleep.
• During the evening fussy hour, together with swaddling and rocking.
• At the nap transition, to soften the everyday sounds of the house.