Posts Tagged acoustic diffusion
Acoustic Transformation at New Harmony: Preserving Art, Improving Sound
Posted by Acoustics First in Absorption, Art Galleries, Articles, Customer Feedback, Diffusion, Multipurpose Rooms, Museums, Music Rehearsal Spaces, Product Applications on April 27, 2026
In New Harmony, Indiana, there is a former Odd Fellows Lodge repurposed as a private residence—the main hall doubles as an event and performance space. Measuring 80 by 40 feet with a 14-foot ceiling, the room features a mezzanine, raised stage, large windows, and an extensive collection of artwork. While visually striking, the space presented serious acoustic challenges.
Acoustics veteran, John Gardner was engaged to address these issues after experiencing a VIP performance tied to a blues festival. The goal was clear: improve the sound without disturbing the artwork or compromising the room’s aesthetic.
The Challenge: Excessive Reverberation and Harsh Reflections
Initial assessment and measurements revealed a highly reverberant and reflective environment:
- Reverberation times:
- ~3.5 seconds at 500 Hz
- Over 4 seconds at 1 kHz
- A pronounced “chatter” or flutter echo that degraded clarity
- Strong reflections from walls, mezzanine face, and windows
- Poor intelligibility for both speech and live music
Further analysis showed:
- Extended decay times in mid frequencies
- A rising frequency response:
- +12 dB from 63 Hz to 6.3 kHz
- High-frequency roll-off beginning near 8 kHz
- Noticeable slap-back echoes from rear wall surfaces
The Solution: Integrated, Art-Conscious Treatments
Given the requirement to preserve the room’s visual identity, all treatments were carefully selected and adapted to blend seamlessly into the environment.
Key treatments included:
- Mezzanine Face – Diffusion
- Installed a series of ArtDiffusor® Model F diffusors
- Arranged in a continuous matrix across the mezzanine face
- Positioned against existing molding for a clean, intentional look
- Purpose: break up reflections and reduce flutter echo without deadening the space
- Rear Wall – Absorption
- Installed Tone Tiles®
- Artist-painted to match the room while maintaining acoustic performance
- Purpose: reduce slap and high-frequency reflections
- Reflective Wall Treatment – Absorption + Aesthetic Matching
- Covered a large reflective wall with Sound Channels® wall fabric
- This material is acoustically absorptive, not transparent.
- Original paintings were reinstalled over the treated surface
- Artwork Enhancement – Distributed Absorption
- Added Sonora® panels (1-inch thick) behind existing canvas artwork
- Turned each piece into a functional absorber
- Created slight diaphragm damping effect due to the air gap behind canvases
- Maintained full visual integrity of the collection
- Window Treatment – Removable Absorption
- Installed custom-fit Sonora® panels within window frames
- Panels secured with minimal hardware and used only during performances
- Addressed reflections from large glass surfaces near the stage
Results: Balanced Acoustics Without Visual Compromise
Post-treatment measurements showed clear improvement:
- Reverberation reduced to:
- ~2.1 seconds at 500 Hz
- ~3.4 seconds at 1 kHz
- Reduced flutter echo and slap-back reflections
- More controlled and even frequency response
Performance Outcome: Proven in Practice
The ultimate validation came during the following year’s festival:
- The returning headline performer commented on how good the room sounded
- Performers were able to clearly hear themselves on stage
- Audience members and owners noted significantly improved clarity and warmth
Conclusion
The New Harmony project highlights how thoughtful acoustic design can coexist with architectural and artistic priorities. By using targeted solutions like ArtDiffusor® Model F Diffusors, Tone Tiles®, Sound Channels®, and Sonora® panels, John Gardner successfully transformed a challenging space into an acoustically balanced performance environment—without compromising its character.
Big vs. Bigger: 2′ vs 4′ Acoustic Diffusers
Posted by Acoustics First in Diffusion, Product Applications, Products on December 16, 2025
A couple common form factors in acoustics are based on building material sizes. Ceiling grids are a common place to install acoustic devices, and you will find that many are built to either work in a 2’x2′, 2’x4′, or 4’x4′ ceiling grid installation. This makes sense, but did you know that these devices also perform differently in some cases due to their dimensions? This is especially true with acoustic diffusers.
When you’re tuning a room—whether it’s a studio, theater, rehearsal space, or even a high-end listening room—acoustic diffusers are one of those rare tools that improve clarity without taking the life out of the space. Designs like the Double Duty Diffuser, Pyramidal Diffusers, and Quadratic Diffusers all share that same mission: redistribute sound energy so your room feels open, natural, and honest.
But while they may look similar in concept, their size changes the game. A 2’x2′ panel and a 4’x4′ panel both diffuse sound, but their effect—especially in the low-frequency and low-mid ranges—can be very different.
2’x2′ Diffusers — Compact Control
2’x2′ units are the most modular diffusers in the lineup. Their smaller footprint makes them ideal for:
- Breaking up mid and high-frequency reflections
- Treating small and medium rooms
- Sitting comfortably in grid ceilings or tight wall spaces
Because of their size, 2’x2′ diffusers don’t interact as much with the low-frequency energy in a room. Bass waves—being physically large—tend to wrap around smaller objects. The result? Excellent clarity improvements in the mids and highs, with a very predictable diffusion performance. The Double Duty Diffuser and Pyramidal diffusers have been a standard in breaking up planar surfaces for decades. While their diffusion in low frequencies is limited at this size, the air cavities do help control some upper bass frequencies through absorption.
The tuned mid frequency effects of the 2’x2′ quadratic, and the smooth performance of the Double Duty or Pyramidal diffuser are perfect for control rooms, edit rooms, drum booths, and anywhere you want accuracy without sacrificing sparkle.
4’x4′ Diffusers — Where Diffusion meets Bass Control
Now we get to the big ones.
A 4’x4′ diffuser is similar in concept to its smaller relatives, but the scale moves it into a different acoustic category. At this size, diffusers begin to influence longer wavelengths, which opens the door to something smaller diffusers often struggle with…
Low-frequency interaction
Large diffusers present enough depth, volume, and surface area to affect the bass spectrum. The extra size creates cavities which are tuned to reduce bass, and they have surfaces large enough to redirect those lower frequencies.
- Break up standing waves in the low-mid range
- Reduce modes and nodes common in rectangular rooms
- Add a sense of openness to the bass field
- Prevent buildup behind listening positions
In other words: same diffuser concept, very different low-end behavior.
Wide-area coverage
A single 4’x4′ panel can modify a huge portion of a wall, creating an even, spacious character that feels less like “treatment” and more like a room that’s naturally well-behaved.
These panels shine in larger studios, live rooms, and worship spaces—anywhere you need diffusion that reaches deeper into the frequency spectrum – and can break-up large, flat, specular surface reflections, which are responsible for flutter, echoes, bass buildup, and long reverb times.
Which do you need?
There are two main factors in the decision: space and performance requirements. In certain environments, it’s impractical or impossible to install large 4’x4′ or larger diffusers; It also may not be the best solution – even if it may appear to be on paper. While a single, large barrel diffuser may appear ideal, you may not have enough physical space to allow the diffusion to develop – where several smaller diffusers would be the better solution.
In short, your physical space and acoustic conditions will dictate which size elements will give you the most benefit in your environment.
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.
Eight very different 2′ x 2′ sound diffusers.
Posted by Acoustics First in Diffusion, Product Applications, Products, Recording Facilities on June 30, 2025
Acoustics First® has maximized the idea of adaptable designs. One of the most common modular architectural elements is the 2′ x 2′ ceiling grid. While standard, fiber ceiling tiles have their uses, specialized acoustic environments require higher-performing materials – for both absorption and diffusion. While Acoustics First® excels with its Sonora® and Cloudscape® Ceiling tiles, today we are going to focus on the wide range of 2’x 2′ diffusers that have been developed over the several decades.
Sound diffusers in a 2′ x 2′ format have several advantages, other than just being placed in a ceiling grid to help diffuse the ceiling. They integrate well on walls and in arrays, where they can help break up large flat surfaces and help minimize flutter and standing waves from parallel surfaces. While they provide many different aesthetic options, there are also many different functional types of diffusers available in this form-factor to address different acoustic issues, from flutter, bass issues, targeted frequency absorption, and geometric scattering. Let’s look at some of these devices and their uses.
Geometric Diffusers.
Geometric diffusers have been around a long time. These devices break up large flat surfaces and redirect or “scatter” those reflections in different directions. They work great in environments where you need to redirect acoustic energy in a predictable way, and redistribute a specular reflection over a wider area. In a 2′ x 2′ size, you can also get a fair amount of bass absorption, due to the large cavity behind the geometric shapes creating a space that can be stuffed with absorbent material to tune it.
Quadratic/Mathematic Diffusers
Mathematic diffusers are devices that use specific calculations to design their size, shape, and structures to effect their performance. A common type is called the Quadratic Residue Diffuser (sometimes called a Schroeder Diffuser, after its pioneering inventor, Manfred Schroeder). This type uses a Quadratic Residue Sequence that optimizes uniform sound diffusion at specific design frequencies. There are different ways to implement these designs, but two common designations are based on their diffusion patters – 1D or 2D. A 1D Quadratic diffuser mostly spreads energy in one plane, and a 2D provides a hemispheric pattern.
Organic Diffusers.
Organic diffusers are a variation on the classic mathematic diffusers which use different mathematic functions to optimize the diffusion further by creating a smooth transition. Once such method is called Bicubic Interpolation. Instead of having the math restricted to having blocks at certain heights, the interpolation bridges these heights using a function that provides a smooth transition to the next target height. This transition creates unlimited resolution in the frequencies within it’s functional range, providing expanded uniformity throughout its range, and increasing its capabilities. As different frequencies are affected differently depending on their wavelength – the organic diffusers have no hard edges to define their pattern and look differently to different frequencies and energy from varied sources.
These diffusers all have the ability to be used in different types of installations for different reasons. Many of these diffusers are mixed and matched in the same room. You will see these on the walls or ceiling, and placed in different locations. There are rooms with Double-Duty diffusers for low frequency control, Model C for Mids, and Model F for flutter, while other rooms may have Aeolians™ on the rear wall and Model C’s and Model F’s to control the ceiling.
Keep in mind, these aren’t even all the diffusers we have available, these are just the ones specific to the 2′ x 2′ format. The Aeolian™ has a 1′ x 1′ version called the Aeolian™ Mini. There are flat panel diffusers that are hybrid absorbers and diffuser like the HiPer Panel® and the HiPer Panel® Impact. There are even large format versions of the Double Duty™ diffuser, Pyramidal, and even the Quadratic Diffuser.
For more info about these diffusers, read some of our, “Similar, Yet Different Series,” where we go into more detail about our products… and how some of these are similar, yet different!”
If you have any questions as to which products you need to optimize your space, reach out to Acoustics First® and we can help you find which products will be best for your application. Remember that Acoustics First’s® full line of sound diffusers are all made in the USA, with many available in stock for quick shipping.
Why use a mix of objective and subjective goals to make a great sounding space?
Posted by Acoustics First in Articles, Media Room, Music Tracking Room, Recording Facilities, Recording Studio, Studio Control Room on July 30, 2024
With the ability to measure and analyze every detail of an acoustic environment, sometimes we forget about the basic fact that it should sound the way we want it to sound. There are scenarios where objective measurement is important, desired, and even required. If there is a physical safety concern that may damage hearing ( loud noises, machinery, etc.), a need to have safety information understood (evacuation/safety notices or alarms, etc.), absolute sound privacy is required (HIPAA regulations, government security, or legal need…), or the need for speech clarity for education… often we require some guidelines be met to insure the acoustics meet a decided standard for performance. These standards use objective measurement and data to make these determinations. There isn’t a governing body that regulates how your home theater should perform, or how an office needs to sound (beyond the safety and privacy concerns mentioned above.)
Entertainment venues, theaters, churches, commercial spaces, restaurants, offices, and residential spaces have very little regulation, and while there are many occasions that testing is used to improve the performance of these spaces, there are some environments where the effort to measure and quantify everything can get in the way of the goal of making a great acoustic space. If you wanted to compare different small “critical listening environments” (mixing and mastering studios are examples of these), there would be some general commonalities in their construction and treatment. Many are built to minimize parallel reflections, have short reverb times, symmetric placement of source speakers, control first reflections, and balance the frequency performance of the space.
A “ruler-flat” frequency response shouldn’t be the acoustic goal.
“Balancing the frequency performance of a space” doesn’t mean “attain ruler-flat frequency response across the entire human hearing range.” There are several reasons that the “ruler-flat” interpretation is counterproductive – the first being that it is nearly impossible to attain in any room. Second, is that everyone perceives sound differently. As humans age, almost all people will experience some degree of “presbycusis,” which is slow decline in high-frequency sensitivity that comes with age. If you are lucky enough to reach a ripe old age, there is a 60% – 80% chance (depending on the study you read) that your high-frequency hearing won’t be what it was when you were young. But even with that factor removed, when your hearing was at its best, your personal perception of sound is different from every other person – making sound, by definition, subjective.
The closest you can get to ruler-flat performance is to remove the room entirely and get some high quality headphones – but you may still find yourself tweaking the equalization curve to your preference. There are many people who feel that headphones sound unnatural, or that they are uncomfortable to listen to for long periods of time. Even the best mixing studios are not completely flat. Also, you will see many different sets of speakers in these spaces… or even headphones. These different sources are to compare how a mix will sound in different environments… and that the mix will “translate” in different listening scenarios. These environments which people will listen to music in vary to include outdoors, bathroom, kitchen, movie theater, grocery store, car, truck, SUV, convertible, living room, and more… coming from sources like phone speakers, headphones, assistants like echo and Google, bookshelf speakers, sound bars, audiophile equipment, movie theater sound systems, and an array of automotive audio systems.
Start with the basics.
If you are making a space for critical listening, there are some objective guides that will help you. If building from scratch, build with a geometry that will reduce room modes and parallel surfaces. Reduce reflections that will interfere with the source. Reduce reverb time. Control the bass response to reduce build up. These can all be readily calculated, measured, and controlled with bass traps, absorption, and diffusion. Most of the time, just following these objective guides will get you a room that will sound subjectively “good.”
After you get that far, you could continue trying to measure the room and tweak the performance to try and attain the unattainable ruler-flat response… or you could listen to music in your room and decide with you ears what should to be done to make it sound how you want. There are many subjective arguments people make about why they think something sounds better. There are philosophical arguments about listening to it “as the engineer/artist intended.” There are debates about if you should equalize music at all – even if you are in the majority of the aging population who may need to give the high-frequencies a nudge to experience the sizzle of Stevie Wonder’s glorious high-hat mastery.
When it comes to your own space… if it sounds good to you… it’s right. By following a few objective guidelines to get you in the arena, you can tweak the last bit with your ears until you are experiencing the material the way you prefer it to sound.
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