Processing

Checking simulation vs reality

With VituixCAD one can simulate obtaining an in-room Impulse Response, with a bit of extra work. By modeling not only the arrays, but also their floor + ceiling reflections (as mirrored arrays) I can save an impulse that we can plot with APL_TDA to see what the theory tells us. In short: checking simulation vs reality. Maybe a picture can help visualize this.

Imagine sitting on the couch at the listening position and looking at the arrays in front of you.

Visualize the floor and ceiling as (perfect acoustic) mirrors. From our listening position we hear parts of those floor and ceiling planes as reflections. I’ve mirrored the arrays in both planes to visualize that. That’s the basic idea that was put into the VituixCAD simulation. Instead of only looking at the speaker, VituixCAD now calculates the speaker + floor and ceiling reflections as one ‘system’.

Here one sees what that looks like for our prediction. The black line above is what’s predicted as the in-room frequency response (reflections are set to be 100%, as a worst case scenario).

Let’s see what effect that has on the predicted vertical directivity:

Simulating my reflections this way in VituixCAD let’s me save a simulated IR of the speakers with their floor and ceiling reflections included. Now I can have something that I can compare one-on-one to my in-room measurements.

I’ve put the resulting IR from VituixCAD into APL_TDA and saved it with the earlier measurement as an animated gif to compare the simulation to the actual in-room measurement:

One note to think about: our VituixCAD model here only contains the floor and ceiling reflections of a single array. The in-room measurement contains the floor and ceiling effects of both arrays plus the entire room response from all other surfaces and furniture out in the room. I’d say that this exercise  does show simulations to be quite a useful tool and it is dependable as long as you start with the right input to work with. For me, simulation has been an indispensable tool to learn from, showing me why my in-room measurements looked like they did.

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