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Comment by WithinReason | Hacker News Reader

Directional audio is produced by sound interacting with your ear, so this would not produce spatial audio (unless you would wrap your head in the thin film speaker). What you want is 1 speaker per ear and a software modelling of the HRTF: https://en.wikipedia.org/wiki/Head-related_transfer_function

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That's not what he means, he means using wavefield synthesis which is actually trying to reproduce the physical sound field with speaker arrays, in that case you don't need HRTF processing because your ears are receiving the waves from the actual positions. It can work for a bigger audience in an larger area without wearing headphones and without using head- and position-tracking but it needs lot of loudspeakers for accuracy.

https://en.wikipedia.org/wiki/Wave_field_synthesis

http://www.eliasmerino.com/structural-wfs.html

https://audioxpress.com/news/holoplot-launches-wavefield-syn...

Yeah, instead of 5.1 or 7.1 surround you could have 500.1 or 1000.1 and have soundscapes that are virtually audibly indistinguishable from actually being in the location.

Maybe overkill for movies but for VR immersion that could be fantastic, especially if the modules could be rigged to use Bluetooth 5.0 so that they would only need to be paired to your computer and mapped out in software the way multiple monitors are mapped out in windows.

For VR you could just use a pair of headphones with HRTF. This is what that can sound like:

https://www.youtube.com/watch?v=WYdIidUIbAs

Those are great for spatial audio, true, but they are simply not capable of making sound seem like it is directly in front of me. Some sound comes in through the nose, not a lot obviously, but enough that headphones are dramatically bad at generating sound in front of you.

Plus, given enough calculation and precision, you could create areas that are nearly sonically separated from each other using wave cancellation, and as people move through the space it would change the sonic characteristics of the space and create new vibes.

There's a lot of untapped awesomeness in the audio world, we just need to tools to craft them

Check out the video I linked then

I did. It never sounds like it's in front of me. It's not capable of making sound in such a way as so the sound feels like it is directly in front of me, it's always to the sides or behind me.

Maybe other people feel it, but I do not.

Well, I tried with some one else who also didn't feel any spatial effect. I think it depends on whether the binaural recording was done with a head/ear shape similar to yours. So you'll just have to take my word for it that the audio positioning is very accurate. A good HRTF implementation should be calibrated to your head, Sony was talking about that when discussing the PS5's spatial audio: https://youtu.be/ph8LyNIT9sg?t=2979

I do feel it behind me, around my head, but I don't hear it coming from in front of me. It never crosses the threshold to be audibly in front of me because microphones cannot send sound in through my nose or vibrate my face.

The sound can sound the same as if it passed through your nose and face though. The model head they recorded this with had a different nose and face than yours, but you face could also be modelled in an HRTF.

I think op is talking about beamforming when he talks about directional audio, where a large array of speakers would allow you to e.g. send audio in one direction only. The more speakers, the tighter the control.

I think OP means e.g. a video call where each person's voice is played back from where their mouth is displayed on screen.

I don’t think OP was saying that, but you are. A video layer could be built on the gridlines between the speaker domes. Might need to be quite a large screen for the spacing to work out right. Not for high def video, but good for large displays like talking billboards (ugh, actually).

urgh actually, indeed

Or as a Center Speaker in a cinema setup where the voice comes not from "the middle" but out the mouth of an actor

That would be great, but doesn't really need new speaker technology, at the scale of cinema screens - not like you need pixel granularity - just the encoding to support it. When I had a Saturday job at a cinema a couple of the screens had the centre speakers behind them iirc, it just wasn't an individually addressable array.

Having said that, I suppose Atmos already implicitly supports it, isn't the idea of it that you can put speakers wherever you want and it remixes appropriately? So if your recording was sufficiently granular that dialogue isn't just all vaguely 'at the front' it could already split between say five (corners & middle) 'centres'?

> isn't the idea of it that you can put speakers wherever you want and it remixes appropriately?

No, Atmos has some tolerance for speaker placement but the general positions are somewhat strict (i.e. 1 Front Center, 2 Stereo Fronts, ...). The idea of Atmos is that given a correct sound setup, a sound can be positioned as an Object in 3d Space within the sound bubble. And that only works to a certain degree. If you want a strong 3D sound effect, the Object pretty much needs to be moving (bullets swishing beside your ear). Static Objects are still somewhat restricted to the edges of the bubble or at least i can hear the 3d effect breakdown when static objects are placed in 3d space as opposed to moving objects

Oh, ok, I see, thanks for the correction.

If you put headphones on you could do that with software without needing special speakers.

You would also need an IMU in the headphones to modify the phase when the listener adjusts or her head. This is an important part of how we discern forward from behind.

Apple already does this via spatial audio for AirPod pro.

And for some reason using that is a pretty weird experience. I've been so conditioned not to expect it that I actually turn it off to make it feel "natural"

It’s a weird experience, a bit uncanny valley like. I was using while watching video, and it’s somewhat eerie to turn my head and still have the audio from the earphones “pinned” to the screen.

While that's certainly one way to synthesize directional audio, the far more common way is to actually have the audio come from the direction it's supposed to and let your ear do its normal thing to sort it out. Imagine you had an entire room wallpapered in individually addressable tiny speakers, you could actually project sound from any angle. The added benefit being that it would work for more than one person in the room. we've gone from 2.1 audio -> 5.1 -> 7.2 -> atmos 11.2. Why wouldn't we want to go to 50000.2 audio as the next extension?

Atmos is not 11.2! Home theater Atmos is 12 statically positioned streams, usually 7.1.4 (horizontally_emitting.low_freq.vertically_emitting) and up to 20 dynamically located streams. The audio is then rendered for the speakers configurations. Highest-end decoder can theorically support 24.1.10 but I never saw a decoder support more than 32 channels.

My receiver has 13 outputs (11 amplified, 2 sub at line level) but I use a 5.1.2 configuration, in a relatively small listening room, and I don't know where I could add more speakers without rebuilding the walls and the ceiling.

That would require a lot of wire and a lot of amplifiers. I bet we'll see an installation or two of the proposed design for proving it can be done.

Still, I bet most spatial audio systems will use software and fewer drivers ( potentially these drivers) to create the intended effect.

It just costs too much to wire all them up.

But at thousands of speakers you don't need as much amplification for each wire and considering how these flat speakers are produced, it's not too unlikely that we could eventually be able to embed chips/controllers into then just like we do with current display tech.

With that setup you could encode hundreds of channels in a single wire and each embedded controller would be responsible do decode it's addressed channel(s) to send to it's respective "speaker(s)". If the signal produced isn't high enough, you may also add in some small amplification stage in the embedded chip.

Very interesting. While I disagree with the implementation details, you do bring up a great point I completely missed. Embedding electronics into these would be trivial, thus enabling some form of smart communication removing the need for discreet amps and removing most of the labor involved in installation. Man I love HN.

Angular resolution is all very well, but what about spatial resolution? Even from the same compass bearing, a noise coming from a mile away sounds very different than someone whispering in your ear.

Playing with phase, I imagine that gangs of speakers could be used to produce bass as well. Don't need to stop at x.2...

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