Recent content by Delrin

Here's an old but very informative thread on a successful Helmholtz absorber project that gives lots of build details, great references, and testing results. It meets pretty much all the criteria I listed earlier. It's worth reading the thread from start to finish if you're interested in...

One interesting point about the PDE solutions described above is that the resonance frequency is determined by finding the lowest frequency at which there is a local maximum in the computed cavity pressure (in Pa). Helmholtz resonance occurs at the frequency when the inertial resistance of the...

I used Mathematica to solve the wave equation for the box resonator that I tested at the beginning of this thread, for both a single "cell" and the full array: The calculated resonance frequency was 47.8 Hz for the single cell and 48.4 for the "array" that I actually built. The frequency...

Managed to get it working using a 3D CAD model instead of 2D drawing primitives: The predicted resonance frequency is the same, at 44Hz, and the frequency response plot is identical to that obtained using the 2D drawing and axial symmetry. Scaling of the SPL map is arbitrary, but the overall...

I adapted Mathematica's Helmholtz Resonator tutorial example to the geometry I used earlier with flared ABS pipe sections. I just used a measuring tape and calibers to quickly note the dimensions within the nearest millimetre (actual precision is probably more like 2mm). It came out pretty...

I wanted to mention a couple of caveats related to the simulation approach described above. This is a departure from the thread's topic of understanding Helmholtz resonators, but the simulation concepts are relevant and might be of interest should others wish to experiment with this. One thing...

So after further experimentation with Mathematica I was able to get some initial visualizations of the room modes in the space where I have been doing my measurements (known to have a bad acoustic geometry). I use Autodesk Fusion 360 for a lot of stuff at work, and it was pretty easy to make a...

I didn't hear back from Wolfram yet, but you are right Don that it's a path issue. On MacOS, the "Support Files" referenced in some of the acoustics examples are installed inside of Mathematica's "application bundle"...

Sarumbear you are conflating some initial tests that I made in the past with a set of aspirational recommendations that I posted in regards to how future tests might be carried out and reported. It is evident that my initial tests did not meet all of the guidelines that were subsequently laid...

To be honest, I don't think I ever said my approach was "scientific" and have no need to brand it as such. Some problem-solving techniques may or may not be borrowed from science, engineering, or from plain common sense. Don't get me wrong - I think there is merit in much of what you suggest...

Hi Sarumbear, A scientist understands that applying math without a solid grasp of the underlying concepts is pointless. Math is like computers in this respect: if you put garbage in, then you will get garbage out. A scientist also freely admits when they don't understand something, and tries...

Ok I am way too slow... now I get the joke, which is subtle but hilarious :D. Sorry for the gratuitous lecture on wine bottles and measurements - my bad!

:D You might have missed it, as this thread has become rather long and my posts are admittedly verbose, but I have tested bottles and they are fantastic resonators (all of the physical characteristics of resonance are easily demonstrated). It's just that, in my experience, a few bottles placed...

Measurements or it didn't happen ;). I know this is annoying to some people, but there are just too many anecdotal claims on this topic in my view.

A scientist will know a good source when they see it. I can digest the material easily enough to understand that it's a much more solid basis for the simulations presented than other references I have seen. I have no worries that I can apply this information to develop a more rigorous...