Shushing sound for baby

What this sound is

Acoustically, shushing is white noise shaped by a human mouth: the broadband hiss of breath forced between the teeth, softened by the mouth cavity and concentrated in the mid-to-high frequencies. What separates it from white noise is that it is not continuous: the shhh swells like a breath, leaves a short gap, and begins again. That swell and fall gives the feeling of someone being there rather than a flat hum. The shushing in Agubu keeps that breathing rhythm and runs for as long as you need. Because it is a high-pitched sound that can turn harsh when loud, the volume rule matters here more than for most sounds.

Why it may help

In the first months many babies calm to a long shhh made close to the ear, a method parents everywhere find on their own. The likely explanation has two layers: the broadband hiss resembles the womb's hum and masks sudden sounds, like white noise, while the rhythmic repetition adds a calming regularity like rocking. Whether a recording works as well as a parent's own shhh is a separate question, and the evidence there is close to nonexistent; even the general evidence for steady sounds is weak and mixed. Still, it is easy to try low once your arm tires or your baby is in the cot; Agubu's sleep log shows what changed.

Safe use

When you shush in your arms the sound is very close to the ear and parents make it louder than they realise; from a speaker, distance and level should follow 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.
• Do not raise the sound to the level of the cry to drown it out; turn it down as your baby settles. A loud shhh is too much for the ear even for a short while.

How to play it in Agubu

1. Open Agubu, go to the Sounds tab at the bottom and tap the Shushing 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: the womb sound or the heartbeat under the shushing completes the feeling of being held. 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 evening fussy hour while rocking; start the sound when your arm and breath run out.
• When moving your baby from your arms to the cot, to keep the same sound through the transfer.
• In the car or pram, when you cannot pick your baby up, as a familiar soothing signal.