Posts Tagged diffusers

Acoustic Transformation at New Harmony: Preserving Art, Improving Sound

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.

Sonora® Panels were made to the exact size of existing artwork and installed behind them to increase absorption without disrupting the aesthetic of the space.

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
ArtDiffusor® Model F were installed in a large array across the mezzanine face.

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.

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Acoustics First­® releases new 3D Model Repository.

For those users who like to design visually, Acoustics First® has released a new 3D model repository at:

https://acousticsfirst.com/acousticsfirst-3d-model.htm

The 3D Model Repository allows users to easily preview and download 3D models for their projects.

Currently, the 3D models are available in .SKP and .GLB format for:

More models are coming soon. The repository is available at https://acousticsfirst.com/acousticsfirst-3d-model.htm or it is linked from any of the diffuser pages listed above.

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You say “Diffuser,” I say “Diffusor”

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.

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Eight very different 2′ x 2′ sound diffusers.

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.

The Pyramidal Diffuser is a classic geometric shape that provides 4 surfaces to break up the acoustic energy, these facets are also asymmetric, which prevents lobing, and reflects energy in different directions.
The QuadraPyramid™ offers the same benefits as the pyramidal, but in a lower profile, and 4 times the number of faces in the same footprint. These offer more control over high frequencies, that respond well to the multitude of smaller faces, due to their shorter wavelengths. These work well in spaces with lower ceilings to help control flutter echoes.
The Double-Duty Diffuser™ is a polycylindrical barrel diffuser, which redirects the energy in a hemispheric pattern. This pattern is easy to predict when trying to help distribute energy to many people – either in an audience, or players in an orchestra. This has the added benefit of a large cavity which works well as a bass trap.

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.

The Quadratic Diffuser is a 1D Quadratic Residue Diffuser that diffuses across the wells. This pattern looks similar to that of a Double-Duty diffuser, but is more disruptive to the phase relations of the reflections and is tuned to a narrower frequency band. These diffusers are often installed with the wells up in the ceiling or wall, which means they do not protrude from the surface, providing a clean flat look.
The ArtDiffusor® Model C is a high-performance 2D Quadratic Diffuser. It uses blocks instead of wells, and has angled caps to further assist the development of the hemispheric diffusion pattern. The Model C is a hybrid Quadratic and Binary design. It is quadratic in the heights and binary in the distribution. This unique combination of mathematic functions and the inclusion of angled reflections adds a new dimension when installing arrays of diffusers to reduce lobing and improve performance.
The ArtDiffusor® Model F is an interesting spinoff of the Model C. The Model F is a specialized low-profile version of the Model C, which uses smaller block structures to tune it to higher frequencies. Like the QuadraPyramid above, the larger number of smaller surfaces tunes this device to frequencies with a shorter wavelengths, in a low-profile design. The Model F is ideal for controlling flutter, ringing and high frequency comb filtering artifacts in spaces with limited space, or specific constraints.

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.

The Aeolian™ Diffuser is, at its core, a classic quadratic diffuser. The main difference is that, instead of limiting itself to the standard blocks and wells of a single size, the surface has been modified using bicubic interpolation. So instead of every frequency interacting with 2″x2″ blocks, they hit a rolling organic surface, which will redirect different frequencies in different ways. The different wavelengths interact and reflect off the surface differently – short wavelengths are more specular and longer wavelengths find a larger section of surface to redirect them.
The ArtDiffusor® Model D is another organic diffuser design, but it uses several different modifications to the standard quadratic design. Most quadratic diffusers start with square or rectangular blocks and wells. The Model D started life as rings of different sizes and spacing based on Maximum Length Sequences that were different thicknesses. Those rings were then raised to different heights based on the Quadratic Residue calculations. Randomness was introduced with Boolean logic, which would add height to some rings while subtracting from others when they crossed each others path. The whole geometry finally went through the bicubic interpolation to smooth the transitions. This completely original design is optimized for mid-to-high frequency diffusion and maintains a highly asymmetric diffusion pattern from any angle, at any frequency within the design range.

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.

Big 3 Studio has Aeolians on the rear wall and black Model C’s and Model F’s on the ceiling above the console.

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.

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Why use a mix of objective and subjective goals to make a great sounding space?

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.)

Listening spaces vary in their construction, and are as unique as their owners.

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.

Ruler-flat response isn’t the goal in world-class mixing rooms… the goal is having a room you can use to make world-class mixes! (Note the variety of treatment and source speakers to create an environment that allows mixing music that will “translate.”)

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.

Tuning a live room for recording classical banjo.
Above: Bass traps in the corners, Sonora® panels on the walls, and diffusers to break up the large flat ceiling… This room is for recording, but it has many materials that will work to improve sound in any space.

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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