I've been interested in multichannel audio for a long time. I have a dedicated 5.1 theater/listening room and tons of discs of multichannel music. I recently got a new iPhone 12 Pro Max, so I decided to pick up the AirPods Max so I could get multichannel audio for headphones. I've jumped through all the hoops to make it work, but so far it sounds *nothing* like my multichannel speaker system.
I signed up for HBO Max and AppleTV on my phone to access Atmos content and decided to do a test. Some of the most immersive mixes I've heard are the ones on the David Attenborough nature shows. Sounds in front, behind, 360 degrees. So I listened for a little bit to the Atmos headphone mix for the one on AppleTV and compared it to the stereo mix on a Netflix Attenborough episode, which is supposedly not in spatial audio.
First I listened to the Atmos one. The head tracking worked pretty well. Birds were swooping down and flying all around. The sound swooped around to sorta match the picture. It sounded very good, but not really the same as what I get in my theater. I struggled to discern any soundstage in front of me or surround behind me. So I switched over to Netflix. It was a show about insects in the jungle- bees flying around all over the place. I was surprised to find that the dimensionality of the sound sorta followed the picture, just like Atmos one. I closed my eyes so the picture on the screen wouldn't influence my perception of direction- It was just very good stereo. No front and back, only left and right. All of the dimensionality was created by my eyes, not my ears. I went back to the Atmos one again and put on the birds again and closed my eyes and held my head still. It was the exact same thing as the Netflix one. Just good sounding stereo.
Today I downloaded an app for Dolby Dimension headphones. It mostly just controls the functions of their particular models of headphones, but it has Atmos music samples that they say work on any headphones. It had a button to switch from Atmos to Stereo as the track played. The screen had a head with glowing stars flying around it to match the music. The stereo one sounded blander and had no flying stars on the screen. As I compared the two, I realized that the mixes weren't even similar. Things that potted back and forth in ping pong in the Atmos mix sat still in one place in the stereo one. (Listen to the opening few seconds of the World song. Those are not the same mix.) I closed my eyes and the Atmos mix without looking at the plasma field and stars graphics zipping around and it turned out to be plain stereo- left/right with no front/back. I googled for more Atmos demos and every one of them had a visual element designed to telegraph how you're supposed to hear the dimensionality. And every one was stereo with left/right and no real front/back.
Here is a link to that demo:
https://products.dolby.com/atmos-visualizer-music/
I kind of like the head tracking, but moving the phone further away from the cans didn't affect depth, only side to side changed if I turned my head. I was hoping for something similar to the Smyth Realiser, which is capable of head tracking and custom HRTF to create true dimensional 5.1 with headphones. It's clear that Apple's spatial audio is not the same as surround sound. I can see why it's limited to video apps on the phone itself. Without the visual element, it would just sound like good stereo. I have to say, the whole thing feels like a con job.
Am I doing something wrong, or is the emperor truly naked?
