'Spatialize Stereo' Feature in iOS 15 and macOS Monterey Simulates Spatial Audio for Non-Dolby Content

[MacRumors]

In iOS 15 and macOS Monterey betas, Apple has quietly included a new audio feature called "Spatialize Stereo" that takes any non-Dolby stereo mix and creates a virtual spatial audio environment out of it.

The addition was first discovered by a Reddit user, who had this to say about it:

I assumed that if they ever did this it would warrant at the very least a mention in a Keynote, but unless I completely missed it today I don't think they said anything about it!

The greatest thing about this is that it supports EVERY audio track. Sure I'd pick Atmos Spatial Audio mixes over Spatialized Stereo every time, but for the moment there are only a dozen or so options for Atmos available on Apple Music, so this is such an amazing feature to have!

It's worth reiterating that Spatialize Stereo is different from Spatial Audio, which Apple brought to Apple Music subscribers earlier this week. Spatial Audio with support for Dolby Atmos creates a three-dimensional experience by moving sound all around you.

Spatialize Stereo meanwhile appears to be Apple's attempt to simulate the effect of having sound coming at you from different directions in a virtual environment. It doesn't utilize Dolby Atmos, but on the other hand it works with basically any content, although you do need AirPods Pro or AirPods Max headphones to access it. Here's how it works in the latest iOS 15 beta:

1. Connect your AirPods Pro or AirPods Max to your iPhone or iPad.
2. Play some non-Dolby audio content on your iOS device.
3. Bring up the Control Center.
4. Long press on the volume slider.
5. Tap the Spatialize Stereo button to enable it.

The same option can be found in macOS Monterey in the Control Center's Sound pane. In terms of sound quality, your mileage may vary, but it at least allows users to enjoy some of the benefits of spatialized sound on anything they listen to, and not just content that officially supports Spatial Audio. If you've been able to compare the two different modes, let us know what you think in the comments.

Article Link: 'Spatialize Stereo' Feature in iOS 15 and macOS Monterey Simulates Spatial Audio for Non-Dolby Content

 

[Kylo83]

I’ll keep stereo special audio ruins music

 

[Kylo83]

Dolby atmos needs 7.2.2 at least, left and right is stereo, it’s a gimmick makes music sound like demos I turned it off

 

[ScreenSavers]

I discovered this yesterday listening to music with my AirPods on iOS 15. It's a super neat feature.

 

[haruhiko]

My 1997 Winamp memory is coming back.
That surround sound plug-in turned every MP3 into broken surround music 😂

“Winamp… it really whips the llama’s ass”

 

[ElliotF]

Am I the only one who finds that stereo sounds better than spatial audio? I played a song, then went into the music settings and switched it between “off” and “always on” as the track was playing and found stereo to be so much better. I’m using AirPods Pro btw.

 

[Canubis]

Cool, looking forward to Spatialize Mono button next… 😉

 

[Kylo83]

Am I the only one who finds that stereo sounds better than spatial audio? I played a song, then went into the music settings and switched it between “off” and “always on” as the track was playing and found stereo to be so much better. I’m using AirPods Pro btw.

Same I hated the special audio it’s a gimmick music can’t be made in Dolby atmos for 2 left and right, it made the volume so much quieter and ruined the songs

 

[Vangeli]

I’d like to see something like a dynamic noise cancellation/transparency spatial stereo feature, where you get the head tracked noise cancelled sound sphere focused at whatever screen you’re looking at but if you look away (like someone starts talking to you or you hear a sudden loud noise), the audio lowers and transparency kicks in. Would make something like what Sony headphones have done for a while with the voice pass through feature a little more seamless. And it’d make you focus a little more. That’d be neat. Maybe have the option to tie it into the new “focus” or “work” status settings so it isn’t enabled all of the time.

 

[Saturnine]

Oh, I hadn't realised this was a new feature in iOS 15. I was discussing it in this very forums yesterday as there was some confusion around 'Spatialise Stereo' and 'Spacial Audio.'

It's no wonder some people had no idea what I was talking about.

 

[IceStormNG]

Am I the only one who finds that stereo sounds better than spatial audio? I played a song, then went into the music settings and switched it between “off” and “always on” as the track was playing and found stereo to be so much better. I’m using AirPods Pro btw.

You're not alone. The thing is: Those headphones don't do real surround even if the the track is a native surround file. You just have left and right. What they do are audio effects that try to mimic the timing difference depending on the sound origin relative to your head.
For that purpose, a "reference head" is taken and measurements are based on that. The more your head differs from that, the worse it works. Our ears are all slightly different and our brain is used to our own ears.

In the end, Spatial Audio is just a fancy name for "virtual surround" which exists since many years. It will and can never be on the same level as true surround with speakers in a room. It will always cause some distortion to the track.
Also: Some headphones are better than others to playback virtual surround.

 

[RamGuy]

Works decently on some songs, but no so much on others. My main problem with this setting is how it affects all audio. Having it on for podcasts, audiobooks etc.. is simply horrendous. Luckily it's quite easy to access it through the control center but its still annoying so I will just end up with having it off.

Some of the Dolby Atmos songs on Apple Music doesn't sound that great either. Some labels have clearly just taken their masters and tossed them into a Dolby Atmos mixer and taken whatever came out of it and dumped it back to Apple. Some songs sounds great and you can clearly tell that some attention was put into the Dolby Atmos mixing. While others haven't done anything and the balancing is just piss poor. Most songs by Blink-182 and Linken Park available in Dolby Atmos just doesn't sound good in Dolby Atmos.

I'm having a real hard time with Apple Music when using Apple Lossless and Dolby Atmos as well. It's stop playing, can't scrub and whatnot. But that might be a iOS 15 issue and not a Apple Music issue as my wife hasn't complained so far and she also have Dolby Atmos and Apple Lossless activated.

 

[kerr]

Was there a problem with just calling it Spatial Stereo or Spatial Audio?

 

[csalm87]

Am I the only one who finds that stereo sounds better than spatial audio? I played a song, then went into the music settings and switched it between “off” and “always on” as the track was playing and found stereo to be so much better. I’m using AirPods Pro btw.

I agree. I really like spatial audio when watching movies and TV shows but for music I couldn't really tell the difference, and it was quieter. I'm assuming this will get better over time, though.

 

[ian87w]

Err... Why? Putting on fake effects on regular audio files never sound good to me.

 

[MacKid]

I love Atmos for movies, but the ”revolutionary” sound of Spatial Audio in Apple Music was already familiar to anyone who owns a gaming headset with a virtual surround button.

Genuinely a little surprised they’ve gone all the way and basically admitted it’s just a virtualizer when it comes to the music. Since subbing to Apple One yesterday, I’ve actually been a lot more impressed by the Lossless sound quality. Hope the addition of head tracking can realize the immersion factor they’re claiming.

 

[mavis]

Am I the only one who finds that stereo sounds better than spatial audio? I played a song, then went into the music settings and switched it between “off” and “always on” as the track was playing and found stereo to be so much better. I’m using AirPods Pro btw.

Same here. The vocals are way too forward, the soundstage seems compressed (I thought it was supposed to sound more spacious!) and the original mix is altered to such an extent (from the songs I checked out) that it sort of ruins some of the nuances that I enjoyed in the songs. If music was mixed and mastered to be played in stereo, I can't imagine transitioning to surround sound (particularly simulated surround!) would sound good in most cases.

 

[xalea]

As a music producer who spends a lot of time and effort mixing to get just the right stereo sound field and 'wall of sound,' putting this kind of crap on top of one of my tracks would make me cry. lol. Please don't dishonor the work of many audio engineers and technicians, mastering experts, etc. by applying this junk to their tracks.

 

[RWil85]

Same I hated the special audio it’s a gimmick music can’t be made in Dolby atmos for 2 left and right, it made the volume so much quieter and ruined the songs

I agree with this…limited testing - but, I thought having the spatial audio on, for Apple Music content that supported it, led to a greatly reduced volume and a very muddy track…and I thought it was supposed to do the opposite? Enhance the effects of each instrument and make songs feel more “live performance-y”?

which leads me to my next [over]thought…

…spatial audio does seem awesome for video content that supports it, IMO…nature shows and tv series through Apple TV+, etc…does this mean we will have to go into control center and to our AirPods Settings every time we switch content and toggle Spatial Audio off for Apple Music and back on for video content And vice-versa?….or….will our devices remember that we have Spatial Audio on/off for various types of content? I see the former being a huge pain in the ass.


(huge side note…not sure if placebo or not, but lossless through AirPods Pro via Apple Music sounded great to me!)

 

[Stuey3D]

What this is is a matrix decoder for AirPods.

Think of it as this:

Spatialise Stereo is the equivalent of running a stereo signal through a Dolby Pro Logic/Dolby Surround decoder. What this does is creates a surround sound effect using an algorithm to decode certain frequencies from a stereo source. When done well on a home cinema system this sounds very good, I use Dolby Surround for everything, the higher the quality of the source the better it can accomplish this, and in the case of Dolby Surround at home it can do it with everything from stereo - 5.1/7.1 and create an Atmos like experience by simulating the higher channels.

Dolby Atmos files are using what is called discrete object information, in the old Dolby Digital 5.1 days this would be discrete channel data whereby a mixer can push data to an individual speaker to make a specific sound field.

In the history of cinema audio it went mono - stereo - Dolby Surround (matrixed surround from a stereo source) - Dolby Digital (a true 5.1 audio system with discrete channel information) - Dolby Atmos (object based which allows for varying different speaker configurations to obtain a similar level of immersion)

 

[Sebosz]

So to utilize these new features I have to have either AirPods Pro which are incompatible with my ears (had to return them because of their in-ear design, kept falling out) or very expensive AirPods Max? Geez 🙄 I hope they release 3rd gen of AirPods which will support special audio because I can’t and won’t use in-ear buds. Too bad Beats Solo Pro don’t support this, I love these headphones.

 

[sflagel]

I like Spatial Audio for music - the bit that sets a virtual soundstage to make it sound like you are listening to the music on speakers, instead of in-earphone that make the music sound like its in your head. So music coming from the front. with a broad soundstage.
Atmos, the "3D sound", at least how its been implemented in the existing music seems a gimmick.

So I would love to have

Music on iPhone or external speakers: stereo
Music on AirPods Pro: Spatial in stereo

Movies on iPhone or ATV speakers: Atmos
Movies on iPhone or ATV on AirPods Pro: Spatial plus Atmos

 

[RamGuy]

In the end, Spatial Audio is just a fancy name for "virtual surround" which exists since many years. It will and can never be on the same level as true surround with speakers in a room. It will always cause some distortion to the track.
Also: Some headphones are better than others to playback virtual surround.

One massive difference with "native" Dolby Atmos tracks on Apple Music is that the source has been mixed with Dolby Atmos in mind from the getgo.

Sure, you are virtualising when playing back on headphones as you only have two speakers. But comparing this to the age-old surround virtualisation we have had for years isn't fair.

If you are using a Windows PC and run old surround virtualisation tech like Dolby Headphones or Creative CMSS:3D that have existed for a very long time, you apply it to music from iTunes or whatever. You are taking a 2-channel source and apply algorithm/DSP, trying to map it to 7-channels, and that is then being played back and simulated by your 2-channel headphones.


With Dolby Atmos tracks on Apple Music, Apple receives new masters from the record labels where Dolby Atmos is already in the source. How much time and attention the labels and producers have put into their Dolby Atmos mixing will differ. But Apple is receiving source material directly with Dolby Atmos metadata attached.

There is no algorithm/DSP trying to redefine how this 2-channel source should be upsampled to 7-channels. The labels and producers themselves have worked directly and attached the metadata telling Dolby Atmos what should be played where within Dolby Atmos 360-degree sphere of sound.

Obviously, when being played back on a pair of 2-channel headphones, you are still faced with simulated playback. But the whole idea behind Dolby Atmos is to have a reference format used by the creators and throughout the entire playback chain. When using headphones supporting Dolby Atmos, the headphones are supposed to follow the Dolby Atmos spec and be capable of interpreting and handling the Dolby Atmos metadata. So even though it's still simulations, the source and the simulation being done are talking the same language, providing a much more cohesive and better experience overall. The source contains the metadata telling the headphones exactly where in this 360-degree sphere the audio is supposed to come from, and Dolby Atmos capable headphones are supposed to simulate this with decent precision. It's not pure guesswork like it was with things like Dolby Headphones etc., back in the day.


Dolby Atmos is not like your regular surround either. Dolby Atmos doesn't limit itself to the old static notion of 5-channel, 7-channel surround. With Atmos, you have this 360-degree sphere, and you can mix your playback to have sound coming from any point within this sphere. You can have up to a total of 128-channels per track. Even if you have 12-channels in your home theatre, a Dolby Atmos track will most likely contain metadata that exceeds the number of static channels you have in your setup. But if your home theatre supports Dolby Atmos, it should read this metadata and apply simulation using all the channels you have available to try to do whatever it can to achieve best the playback information contained in the metadata.

If it was just virtualisation there would be no need to have Dolby Atmos tracks on Apple Music. Apple could just implement the spaceilised setero feature and virtualise all the 2-channel tracks into "Spatial Audio".

 

[RamGuy]

So to utilize these new features I have to have either AirPods Pro which are incompatible with my ears (had to return them because of their in-ear design, kept falling out) or very expensive AirPods Max? Geez 🙄 I hope they release 3rd gen of AirPods which will support special audio because I can’t and won’t use in-ear buds. Too bad Beats Solo Pro don’t support this, I love these headphones.

Only if you want this stereo to spatial audio simulation feature. Proper Dolby Atmos track on Apple Music doesn't require you to have Apple AirPods Pro or Apple AirPods Max. So you can enjoy Spatial Audio on whatever you feel like as long as you are playing back something that is actually Dolby Atmos. It's only the feature where Apple tries to apply some simulation algorithm tacking none Dolby Atmos sources and trying to make them into sound like it was Dolby Atmos.

 

[pauloregan]

An insult to the ears.