Frequently asked.

A room of calm sounds to sit inside: steady tones (432, 528, 174 Hz and more), binaural beats for headphones, and sleep sounds like rain, surf and a fire, with a breathing guide and a timer that fades everything out. Beside it is the part the name comes from: crop circles and ancient figures read as sound, next to the pattern each tone raises in sand on a vibrating plate.

Slowtide began as Chladni Fields, a study of crop circles read as sound. Ernst Chladni was the physicist who, in the 1780s, drew a violin bow along the edge of a sand-covered metal plate and watched the sand settle into figures along the lines where the plate held still. The Plates section runs that idea backwards: each formation sets a tone, and the plate beside it shows the figure that tone would raise. The Resonance Room grew out of those tones, and became the front door.

Yes. Every sound is generated live on your phone; nothing is streamed or downloaded. The only time the app goes online is when you tap a source link or a reference image.

They mask a room. Rain, surf, a stream, wind, a fire, crickets and a fan are built from noise and a few filters and never loop, so there is nothing for the ear to catch on. The tone slider on each one sets its colour in hertz: lower is duller and further away, higher is brighter and closer.

Yes. The beat is made from two slightly different tones, one in each ear, and only exists inside your head. Through a speaker it is just a faint wobble. Theta and delta beats have the best evidence for easing anxiety; the 15 Hz beta and 40 Hz gamma beats are for staying alert.

Some of it, a little. Every tone carries a badge: studied means several controlled studies or a meta-analysis point the same way, pilot means one or two small studies, mixed means the evidence goes both ways, and tradition means a practice rather than a finding. The numbered studies are listed at the bottom of the Resonance Room. Nothing here diagnoses or treats anything.

Low. If someone talking normally beside you is easy to hear over it, you are fine. The room opens at a low level on purpose, and the timer is there so your ears get ten quiet minutes every hour.

Keeping the room playing with the screen locked is sleep mode, the main thing Slowtide Plus is for. Your first lock is free: the room keeps playing for twenty minutes so you can hear what it is like. After that, free fades out when the screen locks and Plus keeps going, with lock-screen controls and timers up to eight hours.

Sleep mode, timers to eight hours, unlimited saved mixes (free keeps one) and plate stills without the small iamra.lol mark. Everything else, including every sound and every figure, is free for everyone.

$0.99 a month, $7.99 a year, or $14.99 once for good. Subscriptions are billed by Apple and renew until you cancel in Settings → your name → Subscriptions, at least 24 hours before the period ends. The app's Manage subscription button in the You tab opens the same screen.

Plus belongs to your Apple ID, not to the app. Tap Restore purchases in the You tab or on the Plus sheet and it comes across.

A one-off thank-you. It unlocks nothing; it keeps a solo project going.

Whatever is playing right now, with its levels, tones, timbre, beat and timer: tap Save mix in the Resonance Room and name it. Saved mixes appear as a gallery in the room and in the You tab; tap one to bring it back. Free keeps one, Plus keeps as many as you like.

Hold an empty part of your Home Screen, tap + and search for Slowtide. The small widget plays your first preset or mix; the medium one shows four. Tapping any of them opens the app and starts it playing.

Work sprints with the room. Pick 25·5, 50·10 or 90·15 in the Resonance Room: the room plays through each sprint, dips to a murmur for the rest with a soft chime at each turn, and takes a longer rest after four rounds. If nothing is playing it starts the Work preset: a brook for masking and a low 174 Hz carrier split into a 15 Hz beta beat.

Optional local notifications, set in the You tab: a wind-down reminder at a time you choose, and a nudge if the room has been quiet for a while. They are scheduled on your phone; nothing about you is sent anywhere. Turn them off in the same place, or in Settings → Notifications.

On the free plate, it listens live to find the pitch and overtones of whatever you sing, hum or play, drives the plate with them, and discards the sound in the same instant. Nothing is recorded, stored or sent. See the privacy page.

They are real formations, photographed and mapped; every one has a dossier with its location, date and sources. What they mean is not a question this app answers. The reading into sound is a construction: the geometry sets a fundamental and a stack of partials, and the plate shows what that tone would do to sand.

Because a round plate can only ring in the modes a round plate has. Why this shape, on every figure, says how close the plate can come to the original and why.