Acoustic Diffusion

Acoustic Sound Diffuser – Adds A Nice Touch to Room Acoustic

Acoustic Sound Diffuser

What is an Acoustic Sound Diffuser?

Sound diffuser is an acoustic treatment device for scattering or diffusing of sound energy to reduce flutter echo and comb filtering. When sound bounces or reflected off a flat and hard surface, the reflected energy level is almost similar to the state before it hits the hard surface, and travels in the same composition but opposing direction. As a result of this reflected sound, standing waves and flutter echoes are created and interfere with the original sound produced. This distort sound clarity.

With a sound or acoustic diffuser, the reflected sound is scattered in all direction, thereby diffusing the sound energy without removing it from the environment. Hence, sound clarity is maintained and improved acoustics. For example, in a control room diffusers are generally place onto real wall behind the listening position to reduce reflection from that wall and make the room more lively and sound larger than it really is.

Sound Diffusion vs Absorption

The difference is in the preserving of sound energy within the environment. Sound diffuser don’t absorb sound, they simply disperse the reflected sound waves, distributing the sound energy within the room. For this reason sound diffusers are made of hard materials with corrugated surfaces that are meant for breaking up the sound reflection. Since diffusers don’t absorb sound, you get almost the same amount of energy as it’s been produced.

Whereas, sound absorption is basically the “soaking up” of sound energy. Sound absorbers are typically made of acoustic foam and mineral wool, such as Aurlex’s Studiofoam and Rockwool fiberglass board. Sound absorption is necessary for removing the unpleasant “glare” in sound or bright sound that usually happen on high frequencies. Low frequency sound energy absorption is in bass trapping which frequencies can be down to as low as 40Hz. Acoustic panels are great for mid to higher frequencies in acoustic sound absorption as it can also help in reducing standing waves and flutter echoes.

Sound Diffusion For Small Room

All domestic size rooms need absorption more than diffusion, especially at bass frequencies. Many rooms are treated entirely with absorption and there’s nothing wrong with that. In fact, most acoustic problems can be solved using only absorption. But if cost is not an issue, sound diffusers can add a nice touch and can make a room sound even larger than it is. Unfortunately, good diffusion cost more than good absorption. The less expensive diffusers generally, are too shallow to work to a low enough frequency. To be useful for music applications, a diffuser needs to be at least 2.5 inches deep to be useful.

The conventional wisdom is that sound diffusers should never be placed close to an instrument, microphone or listener. As a thumb of rule, for each inch of diffuser depth you need to be about one foot away. A very large space such as an auditorium or a live room in a million-dollar recording studio has very different problems than a small room, which most people record and listen in. In small rooms, it is difficult to get much distance between the performers, their microphones and the room surfaces. So diffusers that work well at close distances with less audible artifacts are more appropriate for people recording and listening in small rooms. The Quadratic Residue Diffuser (QRD) is great for small room diffusion with, of course a good combination of proper absorber placement.

George Massenburg's Studio
Renown mastering engineer George Massenburg’s studio

Should You Build Your Own Sound Diffuser

DIY Acoustic Diffuser
Image from

Buying ready made acoustic diffusers can easily rip apart your wallet if you have limited resources to build your first home studio or home theatre. Fortunately, there are tons of information online on how you can DIY your own acoustic sound diffuser with very minimum cost. However, it can be laborious and time consuming to make your own diffuser panels. It can take up to 3 to 4 hours to make just 1 acoustic diffuser panel. So a little time and work management spread over a few days should be sufficient for a couple of diffuser panels.

The most popular material for a diy sound diffuser is hard wood, because of the simple construction and ease to work with. You just need a wood saw, sandpaper, wood glue and lacquer for the finishing touch. Of course not forgetting the hard wood strips and woodboard.

For the acoustic diffuser design, here’s the BBC building specs for a low cost but effective QRD diffusor.

One thing to note though, such diy diffusion panels may not be suitable for ceiling mount due to its weight. Unless you take great care in working out what weight limit your ceiling can support and apply the proper fastening, don’t even try for obvious safety reason. If ceiling mount is not an option, than you will need to go for the light weight polystyrene diffuser like the Auralex T’Fusor, which can be installed on a suspended ceiling grid.

Where to Buy Acoustic Diffuser/Diffusor

You can easily get those ready/factory made audio diffusers (or diffusors) from a professional audio equipment retailer in your location (if there’s one). Always buy from the pro shop so that you are getting not just the products, you will also get good tips or advice on where to place the sound diffuser. Otherwise, your best option would be to buy online. Company like Auralex offers a good range of acoustic diffusers to meet your acoustic treatment needs. Though you can’t buy directly from them, you can still receive all technical support direct from Auralex. You can also request a free personalized analysis of your room from Auralex before you get started. FREE Personalized Room Analysis

Auralex Sound Diffusion Panels

Auralex sound diffusion panels are aesthetically designed and precisely calibrated to meet the most demanding critics’ expectation. As evident from the impressive long list of clients, comprises established recording studios and artistes.

Here’s the complete range of Auralex’s acoustic sound diffusers.

  • T’Fusor Diffusor
  • MiniFusor Diffusor
  • MetroFusor Diffusor
  • ProFusor-II
  • Q’Fusor-II Diffusor
  • Sustain Bamboo Diffusors
  • QuadFusor
  • Hemisphere Diffusor

Want to learn more about the theory, design and application of acoustic absorbers and diffusers? Here’s a great book by Trevor Cox, Professor of Acoustics at Salford University. An easy read for starters into acoustical treatment with diffusers and absorbers.

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