Over the past few weeks we’ve received an increasing number of questions about so-called acoustic pictures, a certain type of acoustic panels that seem to be the latest craze among HiFi and home theatre devotees. In most cases the conversation starts like “I want to make a DIY acoustic picture. Can’t I use that lovely piece of cotton cloth I already have? It’s relatively permeable to air, and the actual acoustic work is done by the absorber behind it anyway, right?
The answer to the second question is a straightforward “yes”. Only the absorber itself influences the sound in a room by absorbing sound waves. From a technical point of view, you don’t really need to cover absorbers at all. Unfortunately, an open absorber is a true eyesore. That’s why you better attach a front cover.
When it comes to selecting the appropriate fabric for this cover, however, maximum sound permeability is the key criterion – for a very simple reason: Only sound waves that reach the absorber can be absorbed. Sounds logic, eh? There’s nothing to be gained from a cover that reflects the sound before it hits the absorber. So our answer to the fist question is equally straightforward: “you better don’t!”
Simple air permeability doesn’t mean much at all. Even a sanforised sheet of mercerised cotton is permeable to air. The key question is the speed at which the air permeates the fabric, or how much resistance it has to overcome. The higher this resistance, the lower the acoustic transparency and the higher the reflection of higher frequencies. Just as you do not want to cover the fronts of speakers with a dense cotton fabric or canvas, you wouldn’t use such fabrics for acoustic pictures that are supposed to do their job properly. After all, there are acoustically effective elements involved in both cases: a loudspeaker, which is a sound wave generator, on the one hand, a sound absorber on the other hand. And there’s a simple rule that applies to all acoustically effective elements: For optimal acoustic results, virtually nothing should be placed between the acoustically effective element and the human ear.
So correct material selection makes quite a bit of a difference. It’s highly advisable to use nothing but high-quality speaker cloth, even if some suppliers of ready-made acoustic pictures staunchly claim the opposite. A handful are really telling porkies when they sell standard stretcher frames covered with printed canvas and filled with absorber material as “effective acoustic panels”. Such constructions are virtually non-transparent to sound. Even worse, they tend to reflect mainly high-mids and high frequencies – which are perceived as particularly annoying, because they make up the essential part of a room’s audible reverb. Okay, the professional audio sector certainly places much higher demands on the acoustic properties of a room than a home user usually does. We can also take for granted that aesthetic considerations in your own four walls are most probably completely different from those that apply in a recording studio or a speaker’s cabin, especially if you’ve decided to build your own acoustic panels. Nevertheless, don’t pour your money down the drain for such iffy stuff.
Our range of Acoustic Cloth has been carefully designed for a maximum of sound permeability plus sufficient opacity. And if you want to design your 100% individual acoustic picture, you’ll be happy to hear that our standard Acoustic Cloth is suitable for printing. All you need is a flatbed printer (which is something every major digital print shop calls its own nowadays). This is the perfect solution for DIY acoustic pictures that combine excellent acoustic property and individual design – all the more so as Akustikstoff.com offers an enormous amount of design options: 42 standard colours plus nine metallic colours.