When will acoustic analysis be implemented in the VASA package?
Or does the VASA package already have the capability for acoustic analysis?
When I was previously told about it in this forum, there was no such functionality.
Happy for the package developers to correct me but I don’t think voxels are the the right approach to acoustics, given it moves in rays/waves and bounces off surfaces via incidence/roughness etc.
May be best off researching the options out there generally vs just in Dynamo - I expect acoustic simulation to be highly complex and computationally costly.
@GavinCrump
Thanks for the reply.
I understand that voxels are not suitable for acoustic analysis.
I would appreciate it if you could explain a little more about “given it moves in rays/waves and bounces off surfaces via incidence/roughness etc.”
Hi, @s.iwasaki!
Did you try acustamo package?
Congratulations to our AU 2014 Dynamo Hackathon winner: “Acoustamo: Designed by Sound” - Dynamo BIM
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This is for the same reason that space analysis doesn’t give decibel values. A quick thought experiment.
Say you have a room with nothing in it, and all the walls and floors are built from concrete. If you stand in the middle it’s going to echo a lot. But if you hang thick curtains along each wall it will echo a lot less. And if you put a drop acoustical tile ceiling up it will echo even less. And if you add carpet. And if you fill the room with furniture and the like… in the end you would still get a bit of echo as you cannot completely remove it, but it would be greatly reduced, perhaps to the point that it is unnoticeable.
Hopefully the thought experiment above drove home the point that the type of material has significant impact on how sound bounces off of it. Scientifically many material qualities impact how sound bounces off of it. At the moment VASA doesn’t have a way to store values on any voxel, because each voxel is stored as a single bit in a flat list. As such it won’t get you that degree of accuracy. In theory it could be used for a 2D analysis similar to space analysis, but at the moment it doesn’t do the 3D calculations. Perhaps @rhys.goldstein (the package author) can shed some more light on the topic or give us his thoughts?
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As Jacob mentioned materials heavily drive acoustics. The way sound travels, bounced and is sbsorbed is complex to simulate and requires pretty full on calculations. As well as this surfaces are imperfect so I’m fairly sure good simulation would not simply let sound bounce perfectly. If you need an example throw a ball along a wall, it doesnt bounce normal to the wall, but incidentally about the normal minus friction/energy loss etc.
Sound moves in waves so also inteferes, amplifies etc. so an effective simulation would need to account for this - not as simple as just bouncing rays independently of one another.
Maybe look into existing software first to get ideas of what can be done, e.g. comsol or Pachyderm for Grasshopper
Geddan has a great tutorial showing Pachyderm in action:
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Brings back memories of physics classes back in school… When do we get to set up the wave pool in the clear tub with the light above it and place some obstructions to study how waves move around and bounce off of the objects?
For those who might want the video: https://www.youtube.com/watch?v=GDwRvv5NZLA
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@s.iwasaki There are basically two ways to simulate acoustics, “waves” or “rays”, as described in this video tutorial:
Tutorial on finite-difference time-domain (FDTD) methods for room acoustics simulation - YouTube
Currently there is no plan to implement an acoustic simulator in VASA, but the “wave” approach in the video is a voxel-based method so it could potentially be added at some point. I can imagine a node that inputs a separate voxel model for each type of surface material, so in theory it should be possible to study the effect of curtains and other sound-absorbing elements on noise propagation. It would be far easier to implement a 2D acoustics simulator that operates on a horizonal slice of a voxel model (i.e. a voxelized floor plan) than a full 3D simulator, though anything is possible.
It would be interesting to hear what applications of acoustics analysis you have in mind. What sound sources are you considering? Vehicle traffic? People talking? Music? Do you need a 3D analysis or would 2D suffice? Do you need to simulate multiple sound sources with different frequencies, or would it be okay to simulate just one point source at a time, at one frequency? How important is it to have precise decibel level predictions?
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