a co-regulation companion
Some nights you're pacing the hallway, the backyard, the whole neighborhood with your crying infant, running out of ideas and running low on yourself. COO was built for that moment.
free for 7 days · no card required · then $3.99 once
when you're calm,
This is co-regulation, the neurophysiological process by which a caregiver's settled nervous system helps an infant's undeveloped one find equilibrium. Infants are born without the capacity to self-regulate. Heart rate, cortisol and breathing rhythms synchronize between caregiver and child. What you feel, your baby's body is learning to feel.
COO is built around this. Each layer is chosen to support your nervous system first, so that support can move outward.
six sound environments
Tap a moment to hear what it's made of.
Calm & Settle
for the everyday overwhelm
every playlist, four layers deep
Nothing here is a generic sound bed. Each layer is picked for what it does to a nervous system, and set at its own deliberate volume.
The womb registers around 85 decibels, a constant low rumble of blood flow and heartbeat. Pink and brown noise mirror that spectral shape, masking the sudden sounds that trigger a newborn's startle reflex. A predictable sound field tells the nervous system there is nothing to brace against.
Pulsed at 68 bpm, a resting maternal heart rate. For a newborn the heartbeat was the first sound, steady before they had any other point of reference. The brain learns to associate this rhythm with safety before it learns anything else.
A tonal lineage roughly a thousand years old, the syllables taken from the hymn Ut queant laxis by Guido d'Arezzo around 1025. COO carries one tone per playlist. These pairings come from that tradition rather than from clinical trials, and we've written plainly about where the evidence sits and where it doesn't.
Alpha, theta or delta depending on where the moment is headed, with a soft melodic overlay on top. The research on binaural entrainment is genuinely mixed and we cite the sceptics too. Every layer sits at a comfortable default volume, and in Premium you can move any one of them yourself.
Lullabies turn up in the ethnographic record across 86 societies, and newborns settle measurably faster with sound. Every source behind this page, including the studies that push back on it, is listed and linked here.
sound mix controls
Every baby braces at something different. Pull the noise floor down, bring the heartbeat up, soften the melody until it is barely there. The mix you land on is the one that works in your house, not the one that worked in a lab.
play all · custom queue
Queue all six playlists into one continuous session and drag them into the order that matches your night. Start in Big Feelings, end in Sleep Wind-Down. Then put the phone down and stop being the one managing it.
nothing hidden
Why 85 decibels. Why 68 beats per minute. Why this tone and not another one. The whole reasoning is in there, in plain language, for the nights you are awake anyway and want to know what you are listening to.
Made for caregivers,
by a caregiver.
keep volume comfortable · device away from baby
