No Diffraction?

[WildCat]

I've been doing some basic testing with the Unity plug-in for the last few hours and the biggest issue that I've found is the apparent lack of sound diffraction (sound bending around corners).

When Direct Occlusion is enabled (either Raycast or Partial), the sound is completely silenced when the source is fully occluded. Even with reflections enabled, it doesn't sound realistic. There's just nowhere near enough sound energy reaching the listener if you hide behind a pillar or just around a corner, for example.

I don't think it's enough for sound to just bounce off walls. A good sound propagation engine also needs to diffract sounds around corners.

It looks like some other people have alluded to the lack of diffraction in their feedback:

• http://steamcommunity.com/app/596420/discussions/0/133258092241133882/
  
• http://steamcommunity.com/app/596420/discussions/0/133258092239876827/

[WildCat]

Here is a video demonstration of the issue I'm describing. (The video is fairly quiet so turn your volume up. The loudest part is 10 seconds in.)

https://www.youtube.com/watch?v=0s6z8zY-d2o

In real life, sound doesn't get so aggressively muffled if you hide behind a pillar.

What happened to the diffraction simulation that was shown in the first half of the following demo video from 2015?

https://www.youtube.com/watch?v=q5MC1FJ1pec

Will that feature be coming to Steam Audio?

In the event that that feature won't be implemented, I had an idea for a simplistic stopgap solution to reduce the harshness of occlusion:

Add a new parameter to the 'Phonon Effect' script (or where ever it's appropriate) called:

'Direct Occlusion Factor'

• This setting can have a value between 0 and 1.
  
• The default setting of 1 will produce the same behaviour as we currently see.
  
• A value of 0 will effectively nullify the occlusion effect even when it's enabled.
  
• A value of 0.5 will cause and occluded sound to be rendered at half the volume that it would otherwise be rendered at if it was not occluded.

[MDA Digital AB]

I've noticed a lack of response to these posts from Valve, a bit worried it means this is the best it going to get. We did a actual play test with our game, and we can't use it in its current state, grenade explosions and fire arm sounds just disperse way too fast. It's really sad because it's such an easy framework to setup. Really awesome in that way

[WildCat]

Originally posted by MDA Digital AB:

I've noticed a lack of response to these posts from Valve, a bit worried it means this is the best it going to get.

I think it's just because we've been posting on the weekend. As I type this, it's 02:30 on Monday morning in Bellevue, Washington. I'm hoping that we'll see some more responses later in the day. Valve acquired Impulsonic and I think that the employees have moved into Valve's offices. I imagine that they will continue to work on Steam Audio.

Originally posted by MDA Digital AB:

grenade explosions and fire arm sounds just disperse way too fast.

In the manual, it says the following on page 6 under the heading "Physics Based Attenuation":

Physics-based attenuation is applied on top of any distance attenuation specified in the 3D Sound Settings of an Audio Source in Unity. To avoid applying distance attenuation multiple times, either uncheck Physics Based Attenuation in Phonon Effect or ensure that no distance attenuation is applied by the Audio Source.

Basically:

• OPTION 1 -- If you want to have 'Physics Based Attenuation' checked on the Phonon Effect script, then you must set the 'Spatial Blend' to 0 (ie: 2D) on the Unity Audio Source.
  
• OPTION 2 -- If you want to have the 'Spatial Blend' set to 1 (ie: 3D) on the Unity Audio Source, then you must uncheck 'Physics Based Attenuation' on the Phonon Effect script.

Furthermore, Phonon's physics based attenuation is not customisable. If you need to use an unrealistic falloff curve, then use option 2 above and customise the falloff curve with Unity's Audio Source.

NOTE: In my testing, I found that the setup described in option 2 will severely mess with Phonon's reflection system. I think you should only use this option if you don't need reflections (ie: if you're just using Steam Audio to get the binaural effect).

[MDA Digital AB]

I'm using option 1 still way too short distance, a grenade just heard a few meters

[lakulish]

I've added a couple of issues on the GitHub issue tracker for this:

https://github.com/ValveSoftware/steam-audio/issues/9

https://github.com/ValveSoftware/steam-audio/issues/10

The occluded sound may be too aggressively cut off in some cases because diffraction and transmission are not being simulated.

[lakulish]

Originally posted by MDA Digital AB:

I'm using option 1 still way too short distance, a grenade just heard a few meters

What is the scale of the scene you're using for testing? Steam Audio assumes 1 unit = 1 meter.

[lakulish]

Originally posted by WildCat:

NOTE: In my testing, I found that the setup described in option 2 will severely mess with Phonon's reflection system. I think you should only use this option if you don't need reflections (ie: if you're just using Steam Audio to get the binaural effect).

I've added an issue to the GitHub issue tracker:

https://github.com/ValveSoftware/steam-audio/issues/11

[MDA Digital AB]

Originally posted by lakulish:

Originally posted by MDA Digital AB:

I'm using option 1 still way too short distance, a grenade just heard a few meters

What is the scale of the scene you're using for testing? Steam Audio assumes 1 unit = 1 meter.

We use real world scales, so 1 unit = 1 meter

edit: Thanks for adding those issues, subscribing to them right away

[WildCat]

Thanks, lakulish. I'm very happy to hear that you plan to add both diffraction and transmission. Once those two features are provided, I think Steam Audio will be one of the best (if not the best) 3D audio system available.

Regarding the messed up reverbs when using Unity's falloff curve, I added a comment to the Github issue with some detail.

[OCASM]

Originally posted by MDA Digital AB:

I'm using option 1 still way too short distance, a grenade just heard a few meters

Grenades are very loud in real life. Using physics based attenuation you'd need to set the volume of that sound very high to get the expected results. That would damage your ears though.

The solution is HDR audio:

http://www.frostbite.com/2009/04/how-hdr-audio-makes-battlefield-bad-company-go-boom/

[MDA Digital AB]

Valve should add a volume override or something on the phonon effect, there is no way that I know of with current version to get our weapons to travel further than for example our VOIP