What is Sound diffusion?
Diffusion can be termed as even Spreading of acoustic energy in an architectural space. An Auditorium with same RT 60 at any listening position is considered as a perfectly diffusive sound environment. Most of the architectural spaces have less to no diffusion; hence reverberation times will be significantly different throughout the room. Low frequencies are extremely difficult to control and diffuse because of their longer wavelength. Let’s understand what diffusers are and how they can help you get better sound in your Recording studio or Home Cinema space.
What are Acoustic diffusers?
Sound Diffusers or popularly known as Acoustic diffusers are acoustical devices that are used to disperse sound energy in different directions; Acoustic diffuser reduces flutter echoes and Low frequency modal resonances. They are generally used in critical listening environments like Studio Control rooms, live-recording rooms and in entertainment spaces like Home Cinemas, Mini Theatres, Preview theatres etc.
Most of the studio and home cinema owners treat their rooms with just absorption. Although this isn’t wrong, it might make the room sound “dull” and “lifeless”. With Sound diffusion you are going to add warmth and liveliness to the sound without deviating from the quest for “Great Sound”.
Usage of Sound Diffusers:
Sound diffusion can act as a perfect alternative to sound reflection. Acoustic diffusers used in conjunction with other acoustical treatments such as acoustic absorbers, bass traps, Acoustic baffles and acoustic ceiling tiles can help you improve the quality of internal acoustics of your Recording studio or Home Theatre.
Acoustic diffuser Types:
QRD: A Quadratic residue diffuser is a true acoustic diffuser in every sense. They are based on prime numbers and comprise wells of different depths. These diffusers are used to scatter sound energy in different yet predictable directions. They are mostly placed on rear walls of recording studio facilities and sometimes on the side walls of a Home cinema room to control first order reflections.
QRD Diffusers are generally placed 6’ to 8’ away from the listener. Deeper the diffuser, lower the frequency it absorbs and width of the QRD slat defines the high frequencies it diffuses.
Poly Diffuser: These extremely easy to build acoustic diffusers scatter high and mid frequencies and also absorb bass. They can be built using either a thin MDF sheet or Flexi ply to create a great looking sound panel. When it is internally packed with high density acoustic materials like Rockwool, Poly Synth etc. they will double up as a bass trapping device. Polycyndrical diffusers are generally used for larger rooms.
Skyline Diffuser: These types of acoustic sound diffusers are called Skyline as they look like skyline of a city. These are built with high quality Pine wood sound diffuser materials and disperse sound in both horizontal and vertical plane. If designed and installed well they can help you get great sound from your Studio monitors and Hifi Speaker system by diffusing high and mid frequencies evenly.
Pyramid Diffusers: These acoustic diffusers minimise standing waves between two walls or floor and ceiling. Constructed using MDF, These diffusers breakup harmful reflections and reduce flutter echoes while providing warm sound. Like Poly diffusers, The Pyramids will also help you absorb bass if their internal cavities are lined with high density Rockwool.
TIPS and Guidelines to build your own Sound diffusers:
1. If you are building sound diffuser panels to scatter low frequencies, Make sure they are really thick and deep otherwise low frequencies will pass right through it. Having said that, I would strongly recommend you to try diffusing high and mid frequencies and build bass trapping devices to control bass.
2. Whenever you use sound diffuser panels, your seating should be placed at a minimum distance from it. For instance, if your diffuser is 8” deep, you should be seated at a minimum distance of 8’ away from it. Similarly, for every inch of the diffuser depth increased, correspondingly does your distance increase by 1’.
3. If you want to render a wider soundstage from your Studio monitors, placing a properly designed sound Diffuser on the front wall between the Left and Right speaker works wonders. In this case, a diffuser than an absorber will prove to be a better choice as they avoid harmful reflections getting mixed with the direct sound of the speakers, while also helping in creating better soundstage.
4. The closer you are to the wall surface, the closer the Poly diffusers should be placed together.
What’s the best place for your Sound Diffusers?
The position of a sound diffuser depends upon various criteria. Acousticians and Audio Engineers are the best to suggest you about its placement after studying and analyzing various acoustical parameters, budget and aesthetics of your recording studio or home theater. Years of experience, simulation and on site acoustical measurements help the acousticians in delivering great sound with sound diffusion.
Image credits: Freepik