
The goal of this project was to create two auditoriums stacked on top of each other. I would then design the structure that supports these auditoriums and do an acoustical analysis. The idea was that the fake roof, made from acoustical panels, could be adapted to make a more acoustically sound auditorium. To do this, I would use the Pachyderm plugin for Grasshopper.


Definement basic geometry auditorium
Firstly I started designing the basic geometry I required from my auditorium and I set up the structural systems. I was planning on using the auditoriums I made for my studio project, that is why they needed to be functional, aesthically pleasing and acoustically correct.


Structural geometry for auditorium (columns and trusses)
Before I could start work on making the fake roof, I did some research into acoustics and which parameters would be important for me, and of course how I would be able to improve these values. Pachdyerm itself has a lot of different outputs like the: Impulse Response, Reverberation time (RT60), Early decay time (EDT), Clarity (C50 and C80), definition, speech transition index, Strength,… But since I plan on using the auditorium for lectures I choose a couple of these to focus on, to make it more manageable.
- Speech clarity (C50). Target: >3 dB. This value measures the balance between early reflection (helpful for clarity) and late reflection (which causes muddiness). The value can be improved by sound-absorbing materials and by ensuring that the reflections from the ceiling are aimed toward the audience.
- Definition (D50). Target: >50%. This value measures how much of the sound arrives within 50 milliseconds of the direct sound, contributing to better speech clarity. The value can be improved by using reflective materials to direct the sound toward the audience in that critical 50-millisecond window.
- Speech Transmission Index (STI). Target >0,6. This is a single number rating for speech intelligibility by considering factors such as background noise, reverberation,… Use acoustical panels to minimize external noise.


Playing with the geometry of the panels
Now that I have a goal, I set up the fake roof with a couple of different parameters, which I played with to create an auditorium that meets my goals. After a lot of trial and error, I was able to achieve all of the values I preset. Now that I have done the acoustical analysis, I can say that the different parameters that I had, the materiality and curvature of the roof, were the most impactful in achieving this goal.


Playing with the size/gap of the panels and the overall shape of the roof

Script used for acoustical panel roof

The full script
Using Pachyderm came with a large set of problems that I didn’t anticipate beforehand. Here I list some of my struggles and how I overcame these:
- The biggest problem was that I set up my whole grasshopper model in mm while Pachyderm was only able to work in meters. I only noticed this in the end, when I had already set up my entire model. I solved this by just using the Pachyderm simulation within Rhino, not the one in Grasshopper.
- Pachyderm not loading or crashing was something that happened a lot. In my experience, this has 2 main reasons: The first is problems with the materials of all the objects, so make sure this is good. The second is a model that is too complex. Eventually, I decided to delete all the parts that weren’t directly relevant to the acoustics.
- It is important to note that while it seems like it is not working or crashing sometimes. It is possible it is still calculating and it’s just taking a while.
- Making the video animation was not able to export and was only able to render a few rays. So I used only a couple of rays and screenrecorded my Rhino preview.
The software is very complex and made for professional usage, as a student who didn’t know much about acoustics it was really hard to understand this sometimes. Tutorials online and ChatGPT were of great help, not only to understand Pachyderm but also to understand acoustics better in general.
Acoustical Analysis Animation
Fly through used for my studio project
Script download