Forest Stream Awakening
A clear woodland stream with birds waking up around it and a woodpecker deeper in the trees.
- Forest Birds & River 50%
- River 30%
- Woodpecker and Birds 14%
Slo vs Portal: Ambient Mixing or Immersive Nature? (2026)
| Feature | Slo | Portal |
|---|---|---|
| Primary experience | Audio layers, saved mixes and a sleep timer | Location-based audio and motion visuals |
| Verified library | 200+ in the app, 89 free; 180 free in the browser | 80+ Premium portals; higher counts appear on other official pages |
| Mix ambient layers | Any number of layers, a volume per layer | — |
| Mix with podcasts or music | Off by default; a setting lets other audio play over the sounds | ✓ |
| Motion visuals | — | Up to 12K capture |
| Head-tracked spatial audio | — | Supported portals and headphones |
| Browser listening | 180 sounds free, no account | Not listed |
| Ads in the browser player | None | Browser player: not offered |
| iPhone, iPad, and Mac | iPhone and Mac downloads | ✓ |
| Android | ✓ | — |
| Offline playback | Yes, after download in the app | Not listed |
| Sleep timer | 15 minutes to 24 hours, fade-out up to 2 minutes | Timers in Focus, Sleep and Escape modes |
| Price model | Monthly, yearly or one-time lifetime | Check localized membership screen |
Pick Portal if you want to sit down and take a break inside a real recorded place, with moving pictures, spatial audio and lights that follow the scene. Pick Slo if you want sound running behind your work or your sleep, with 200+ sounds, 89 of them free, and a timer that fades out after up to 24 hours.
The short answer
Both pages turn up when you search for nature sounds, and the two apps are doing different jobs. Slo fits if you want to set every layer and its volume yourself, keep a timer between 15 minutes and 24 hours, listen on Android, or mix in a browser. Portal fits if you’re on an iPhone, iPad or Mac and you want a session built from a real location, with motion visuals, spatial audio and smart lights if you have them.
Slo is a background you shape while you do something else, and Portal asks for your attention and turns your screen, your headphones and sometimes the lamps in the room into a window onto another place.
How we compared. Portal’s details come from its official website, FAQs and App Store listing, checked July 31, 2026. Its own pages give different catalogue totals, so the table below uses the lowest one, the 80+ Premium figure from its iPhone/iPad FAQ, and the gap is explained further down. We make Slo, and its figures come from the app source, version 3.132, on September 14, 2026. Neither app can guarantee better sleep.
Slo vs Portal at a glance
| Decision | Slo | Portal |
|---|---|---|
| Core format | Mixable ambient audio, any number of layers | Recorded places with spatial audio and motion visuals |
| Catalogue statement | 200+ sounds in the app, 89 free; 180 free in the browser | iPhone/iPad FAQ: 80+ Premium portals; other official pages list 100+ or 120+ |
| Customization | A volume per layer, saved mixes, a timer of 15 minutes to 24 hours | Choose a complete portal; Mix Audio combines it with another app’s audio |
| Visual component | None verified | Motion visuals captured up to 12K |
| Spatial audio | No verified head tracking | Static and dynamic spatial audio; support varies by portal and headphones |
| Platforms | iPhone, Android, Mac; 180 free sounds in the browser | iPhone, iPad, and Mac |
| Best for | A background mix that runs all night and stops on its own | Deliberate nature immersion in the Apple ecosystem |
| Main tradeoff | Less visual and spatial immersion | No Android or browser player; less component-level sound mixing |
On price, Portal changed its membership in June 2026 and says local amounts vary, so this page links its current membership screen. A figure copied here would be wrong for someone reading it in another country next month.
What Slo offers
There are 200+ recorded sounds in the Slo app, and 89 of those stay free. The noise part of the library holds 22 recordings across seven colors, five of those brown, and there are 11 rain tracks and 9 water tracks as well. The mixer takes as many layers as you like, each with a volume you set, and it holds the balance you choose for every combination you build. Save a mix and you can export it as a file and import it somewhere else. The sleep timer runs from 15 minutes to 24 hours, and the sound fades out over 15 seconds to 2 minutes before it stops. Playback carries on as a background audio service on iPhone and Android, with the controls on the lock screen. Play a sound once in the app and it downloads and stays there, which is why a saved mix runs with no network. For the full library you pay a monthly or yearly subscription or buy a one-time lifetime purchase, and 180 of the sounds play free on slonoise.com with no account.
Slo shows you no picture, follows no head movement and talks to no lamp. If the point of the session is to look at somewhere else for twenty minutes, Portal is the app built for that.
What Portal offers
Portal records real natural places and plays them back with immersive audio and moving pictures. Its current official site advertises motion visuals captured in up to 12K, spatial audio, and smart-light support for Philips Hue, HomeKit, and Nanoleaf. On the scenes that support Dynamic Spatial Audio, the sound stays put when you turn your head, as long as you’re wearing the AirPods or Beats models it names.
Portal’s iPhone and iPad FAQ says Premium includes over 80 portals, available on iPhone, iPad and Mac. Its Mac FAQ says over 100, and its Experience page says 120+. The gap may come down to platform, rollout or a page nobody has updated, and the public pages don’t let us settle on one number, so this page sticks with 80+.
Portal also carries Focus, Sleep and Escape modes, timers, breathing exercises, a virtual sunrise alarm, and a feature called Mix Audio. That one plays a portal under a podcast, audiobook, playlist or meditation from another app, which is a different thing from Slo’s mixer, where you balance a rain layer against a river or a noise layer.
The differences that matter
A background or a session
Slo can run behind writing, studying or sleep with the screen off, and the timer ends it somewhere between 15 minutes and 24 hours. Portal gives you more to take in, since you get a named location, a moving image, a spatial recording and possibly the room lights to match. That makes it a good deliberate break, and the picture does nothing for you once you’ve closed your eyes or picked up a book.
Layer mixing
In Slo you stack as many ambient layers as you want and set each volume. Portal hands you the finished place. Its Mix Audio feature lays speech or music from another app over a portal, and it won’t let you take the portal apart and rebuild it from separate natural layers.
Spatial audio and hardware
Portal supports both fixed and head-tracked spatial audio, though not every portal does the head tracking. For that its FAQ names AirPods 3rd generation, AirPods Pro, AirPods Max and Beats Fit Pro. Slo has no head tracking and no spatial mix at all. If the spatial effect is what you’re buying, check your own headphones against that list and look for the tag on the portal.
Platform scope
Portal’s official product pages cover iPhone, iPad and Mac, with no Android app and no browser player listed. Slo has an Android app and plays 180 free sounds in a browser. If you’re on an Android phone, that one fact ends the comparison.
Catalogue numbers
Slo’s 200+ is a count of sounds you can mix, 89 of them free. Portal’s number counts whole destinations, and its official pages disagree with each other, from 80+ Premium on iPhone and iPad to higher figures elsewhere. The two totals count different things, and neither one ranks quality.
Which one should you choose?
| Your priority | Better first test | Why |
|---|---|---|
| Brown noise plus rain at separate levels | Slo | 5 brown recordings and 11 rain tracks, each with its own volume |
| Real-location visuals and sound | Portal | Its portals pair a recorded place with moving pictures |
| Android or browser use | Slo | Portal lists Apple apps only |
| Head-tracked natural sound | Portal | Dynamic spatial audio works on the scenes that carry the tag |
| Background audio during reading | Slo | Nothing to watch, and a timer that fades out |
| Smart lights tied to a destination | Portal | Its site states Philips Hue, HomeKit and Nanoleaf support |
Portal’s visuals and spatial audio can feel more like being somewhere, and that feeling isn’t evidence of better sleep or sharper focus. If you’re doing this to sleep, keep the volume at the lowest level that covers what you can hear, and compare a week of it against a week of quiet. Our nature sound evidence guide sorts the research from the marketing.
Slo nature presets
Compare woodland detail with a broader coastal mix
These two show what Slo lets you adjust with sound alone. Turn down any layer that keeps pulling your attention back to it.
Ocean and Green Noise for Stress Relief
Rolling waves over a steady hiss, for ten minutes when you need the room to feel less busy.
- Green Noise 55%
- Ocean Waves 40%
Frequently asked questions
How many portals does Portal include in 2026?
Portal’s official iPhone and iPad FAQ says over 80 Premium portals. Its Mac FAQ says over 100, and the general Experience page says 120+. Its own pages disagree, so check what your device shows you today.
Can I get Portal on Android?
No. Portal’s official website lists no Android app and currently promotes iPhone, iPad and Mac. If you’re on Android, Slo has an app there and plays 180 sounds free in a browser.
Does Portal let you mix nature sounds?
Not the way Slo does. Portal’s Mix Audio plays a portal underneath audio from another app. Slo’s mixer balances the individual ambient layers you choose, with a volume on each one and no cap on how many you add.
Does every portal support head-tracked spatial audio?
No. Portal says most do and that some early recordings don’t. Look for the Dynamic Spatial Audio tag, and use the headphones its FAQ lists.
Is Portal better than Slo for sleep?
Neither one is better for everyone. Portal gives you a richer visual and spatial session, and Slo gives you a background you can adjust with a timer that runs up to 24 hours and fades out before it stops. Test whichever you pick against a quiet night in your own room, because a stronger sense of being somewhere else is not evidence of better sleep.
Official sources checked July 31, 2026
- Portal, official product site — iPhone, iPad, and Mac scope; up-to-12K visuals; spatial audio; smart lighting.
- Portal, Open Access vs Premium for iPhone/iPad — 80+ Premium portals, modes, timers, Mix Audio, smart lighting, and dynamic-spatial hardware.
- Portal, Experience page and Mac membership FAQ — higher catalogue figures that create the disclosed count ambiguity.
- Portal, Dynamic Spatial Audio FAQ — support varies by portal.
- Portal, localized membership guidance — current tiers and country-dependent pricing.
- Slo app source, version 3.132 (sound list, timer, fade-out and store products), and the slonoise.com sound catalogue, reviewed September 14, 2026.
Related comparisons and guides
Explore more sounds in Slo
Stack two or three sounds, keep the blend, and let the timer stop it. Slo, on iOS, Android and Mac.
