Posts Tagged diffusor
You say “Diffuser,” I say “Diffusor”
Posted by Acoustics First in Diffusion, Q&A, Uncategorized on November 11, 2025
If you’ve spent any time around acoustic treatment—especially sound diffusion—you’ve probably noticed something odd: sometimes the product is called a “diffuser“, and other times it’s a “diffusor“. For newcomers, this can feel like a secret code or a subtle technical distinction – But the truth is much simpler.
Many trace the dual spelling back to Manfred Schroeder, the German physicist who developed the mathematically designed Quadratic Residue Diffusor (QRD).
In German, the word is spelled “Diffusor.” When Schroeder’s work entered the academic world, the spelling likely came with it.
Because his research became foundational in architectural acoustics, the German spelling spread through physics papers, textbooks, and graduate-level acoustics programs. Over time, “diffusor” became a common spelling when discussing mathematical or Schroeder-style diffusors specifically.
As manufacturers began producing these mathematically derived designs—like the ArtDiffusor® line from Acoustics First® (and many other early products)—they retained the “diffusor” spelling as a nod to the academic and scientific origins.
Before long, the industry ended up with two spellings that referred to the same thing:
- Diffuser – the standard English spelling
- Diffusor – the academically inherited, German-influenced spelling tied to Schroeder’s work
Both spellings appear throughout the professional audio world, and both are correct.
Is There Any Practical Difference?
No. None. Zero.
There is no technical difference between a “diffuser” and a “diffusor.” They both refer to devices used to redistribute sound energy and improve the acoustic quality of a space through accelerating the development of sound field diffusion. The spelling variation is purely linguistic.
Think of it like “colour” vs. “color” or “flavour” vs. “flavor.” British English keeps the “u,” American English drops it. (However, if you ask a Brit, they’ll tell you Americans are obviously spelling it wrong.)
The “diffusor/diffuser” split works the same way—just with a German twist.
So Which Should You Use?
Use whichever feels natural or matches the context you’re writing in. Many engineers and academics use “diffusor” when referring to Schroeder-type or other mathematical designs, simply out of tradition. Others stick with the standard English “diffuser.”
Tomato. Tom-ah-to.
Similar, yet different: Angled QRD vs. Standard QRD
Posted by Acoustics First in Diffusion, Product Applications, Products on August 19, 2025
In this installment of “Similar, yet Different,” we explore the similarities and subtle differences between a classic, standard 1D QRD and a modern, angled 1D QRD. While being based on the same mathematic function for their design, there are a couple subtle differences in the performance of these devices.
Quick review. A Quadratic Residue Diffuser is based on a mathematic equation that states that the Well Depth is decided based on the square of the position of the cell and the remainder of when it is divided by a prime number. (We know it sounds really complex… but this is how the ratios of the wells are calculated to maintain a balance of magnitude across the face of the device.)
The equation looks like this:
Well Depth = (n² modulo p)
(Note: there will not be a quiz!)
As it was stated, both of the devices use the identical calculation when coming up with their wells… but there is one important change – the well bottoms are flat on the standard QRD and angled on the angled quadratic. This change makes this diffuser perform differently in 2 key ways:
- The Diffusion Pattern is wider on the angled QRD.
- There is a more subtle transition from one frequency to the next on the angled QRD.
When you look at the two sets of polar pattern above, you will notice that the Angled QRD has a wider pattern, as shown in the first-column, horizonal polar pattern (at 2000Hz especially), where the standard QRD is a more forward-focused pattern.
What does that mean in practice?
Both of these diffusers have a 1D pattern, but the flat bottoms of the standard QRD primarily use diffraction and incidence angle to widen the diffusion… the rest of the diffusion works on the principal of phase offset from the depth of the wells and the time of travel. The Angled QRD introduces an angle which means that one side of the well is deeper than another. This changes the reflection angle, time of travel, and, in turn, degrees of phase shift depending on where the sound strikes the inside of the well. This modification smooths the transition of phase from well to well – as the wells themselves have a range of phase change. This angle also causes the sound to be redirected toward the inner walls of the wells, causing it to change direction from the angle of incidence – widening the pattern further, changing the travel time, and basically bouncing sound around more.
There are some situations where the standard QRD‘s narrow pattern and well-defined transition frequencies may be preferable. In some practice rooms or larger listening spaces, there may be a need for the diffusion to be a little more directional, maybe to hit (or avoid) a certain position in the room. In these scenarios, the standard quadratic may be the recommended choice. In other spaces where you want the reflections to spread out more rapidly – maybe in smaller rooms or spaces where you need to get more coverage from ceiling reflections – then the angled quadratic may be more appropriate.
In closing, while these two devices have a nearly identical design, a small difference can have a big effect on the performance of the diffuser – and how you use them.
Similar, yet Different: Pyramid vs. QuadraPyramid
Posted by Acoustics First in Articles, Product Applications, Products on November 15, 2024
Based on the golden-ratio, offset pyramid… both the Acoustics First® Pyramids and QuadraPyramids have a great deal in common. They are asymmetric in their scattering, which reduces lobing. They have different sized surfaces of different angles, which impose different polar radiation patterns at different frequencies. Both allow for redirection, while allowing much of the signal phase to remain intact, which keeps a great deal of energy moving together, which works great for performance spaces. However, there are some subtle differences which change how these units perform and how you maximize their use.
While both the Pyramidal and the QuadraPyramid come in a 2’x2′ format, the QuadraPyramid packs 4 pyramids into that footprint. That isn’t the only difference though. The depth of the QuadraPyramid is only about 2-3/4″ to the 8″ deep single peak of the classic Pyramidal. On top of that, the Pyramidal comes in different sizes and ratios of length to width including a 4’x4′ and a 2’x4′ at up to 13″ deep.
These different sizes do more than change their aesthetic. The large pyramid geometry allows for greater impact on lower frequencies, as the longer wavelengths are less skewed by small surfaces. The different ratios and sizes also changes the angle of throw off the surfaces, allowing for more options to redirect the sound. The larger surfaces also impose some limitations to their use. Being physically larger means that the listener will need to be further away from the device to allow the reflections to spread out, and the greater depth means that, at certain angles, the geometry can place other devices in their acoustic shadow. The larger pyramids work great in larger rooms with high ceilings, where they can be placed higher in the room. This makes them ideal for performance spaces and large band/music practice rooms – where everyone is spread around and needs to be able to hear everyone else.
The QuadraPyramids have a higher density of reflective faces per square foot. There are 16 facets on a 2’x2′ QuadraPyramid, which means more smaller faces to reflect sound. These faces are optimized for higher frequencies which have shorter wavelengths – but the profiles are actually better suited for smaller rooms with lower ceilings. In smaller studios, listening rooms, and media spaces, space is at a premium, and having a large diffuser hanging a foot down from the ceiling would be more of an impediment. This is where the QuadraPyramids shine. Their low-profile and many facets allow for sounds to spread out while breaking up flutter echoes and reducing other higher frequency artifacts.
Finally, the size of the cavity behind the larger pyramid allows for greater bass trapping, especially with the ability to fill the cavity with fluffy insulation. While the QuadraPyramid still imparts some absorption due to the resonance of the thermoformed plastic material, it is more focused at the resonant frequency (250Hz) – while the larger pyramids have a wider frequency range they affect.
| Device | 125hz | 250Hz | 500Hz | 1000Hz | 2000Hz | 4000Hz | NRC |
| 2’x2′ Pyramid (insulated) | 0.57 | 0.41 | 0.38 | 0.21 | 0.16 | 0.16 | 0.30 |
| 2’x2′ Quadra Pyramid | 0.23 | 0.58 | 0.05 | 0.04 | 0.04 | 0.11 | 0.20 |
While the Pyramid and the QuadraPyramid have their roots in the same geometry, their specific implementation changes their performance characteristics to provide more options in treating your space. Using the right treatment changes depending on the space and its function… even two identical rooms can have drastically different performance requirements – needing drastically different treatments. Acoustically, a Quadrapyramid is drastically different than a 2’x4′ Pyramid – but fundamentally, at their core, they are very similar.
3 Years of the Aeolian® Sound Diffuser
Posted by Acoustics First in Press Release, Products, Uncategorized on July 23, 2020
3 Years of the Aeolian®
It may seem a lifetime ago, but we are celebrating the 3rd Anniversary of the release of the patented Aeolian® Sound diffuser. During development, our team ran numerous models and simulations, revising the design, and optimizing the performance to create the iteration we have today.
The development workflow of the design included computer optimized geometry, performance simulation, rapid prototyping, and full acoustic performance and validation testing. This was one of the first uses of this completed workflow, and while we are always refining our development processes, this was a huge leap forward.
We now look back at the release of the Aeolian® as a milestone in our history, where we developed something more than a product… we developed a better way to design a product.
Here was the original blog post about the Aeolian®.
Happy birthday.
Art Diffusor® Nouveau™ – Limitless possibilities.
Posted by Acoustics First in Diffusion, Product Applications, Products, Uncategorized on June 5, 2020
ArtDiffusor® Nouveau™ on a wall with a dark stain – framed.
Hey! Here’s another installation of our new ArtDiffusor® Nouveau™. For this install, these four boards were not only stained, but also framed out to enhance the design aesthetic. From different paints and stains, to mounting techniques, there are limitless possibilities for customization to create your own unique and functional sound diffusing arrays.
ArtDiffusor® Nouveau™ on a wall with a dark stain – framed.
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