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First experiments. Based on first observations, I tried to use Basotect's pyramid foam panels made by Germany's T- Akustik at the highest part of the sloped ceiling to reduce reverberations accumulating on top of the frame. Regarding the choice of foam, there's no secret. The thicker the better to absorb a broader frequency range. So I went with a 7cm thick 1m square tile. These foam panels weren't easy to fix to a slanted wall because their weight obliged me to use a lot of glue to not end up on the floor. This spoils your wall paint and greatly degraded the aesthetics since you must place them correctly the first time. Their fragility makes them hard to remove again. And these panels will break if you don't pay attention mounting them. T-Akustik offer two colors, gray or white, the latter significantly more expensive as though a premium for discretion. But even in white your imagination has to work overtime to think of these panels as discreet. My wife was incapable of such abstraction and testing these panels lasted one short week. Their absorptive effectiveness above 500Hz as specified by the manufacturer was undeniable but still faded in the treble. Such foam plates seem more properly destined for a recording studio than private listening room.

My main concern was that they were more efficient when placed in highly visible locations (they provide moderate results against standing waves in more obscure places like ceiling or room corners where frequencies pile up at both ends of the audio spectrum). Given the difficulty to reposition them, they also seemed incompatible with the empirical method which requires several attempts before one locates the best compromise on placement. So you will understand that these panels are primarily intended for professional use. But I didn't question their effectiveness in the lower to midrange bands. The absorption bandwidth claimed for them provides a fair idea of their effectiveness.

Portuguese Vicoustic offer more aesthetic panels which don't blend discreetly either. Their effectiveness is similar to Basotect but they are slightly more expensive for their relative elegance. I used them behind my speakers for a long time. They treated back reflections and port issues. Their appearance gives your room a typical recording studio atmosphere despite the finish options to reduce their visual impact. My sister-in-law has no particular interest in my hifi activities thought the first time she saw Vicoustic Wavewood panels, she thought they were modern art.

Despite their assertive aesthetics, the neophyte may indeed believe them to be expressions of a minimalist contemporary artist but they definitely impose a strong identity on your room. And don’t expect impressive results from placing just one or two in your space. You need to cover sufficient surface and at 60cm
² they are relatively small. As they have to be stuck on the wall, they can hardly be used more than once. If you remove a panel to reposition it, you will inevitably tear the foam and probably some of your wall paint with it. You could cut a plate of medium density fiberboard of slightly larger dimensions than the foam board to stick to so the sandwich may be bolted instead. The Wavewood panels combine wood and foam with non-linear sequential cavities to act as both absorber and diffuser. They are said to be particularly effective at treating medium to high frequencies as well as flutter echo. If your intention is to use a limited number of panels randomly, I would rather opt for the more trivial solution of increasing absorption with carpets, heavy curtains and overstuffed furniture. Assuming that you take time to identify critical points, you will undoubtedly have a better result than placing some haphazard panels.

A different approach. The intrusive nature of conventional acoustic panels added to their positioning issues had me focus on an original very easy-to-use product. PYT panels are distributed by a young French entrepreneur. These are very thin and discreet and thanks to a Velcro fixing system easily repositioned. They partially offset their low thickness with three layers of different densities. This triple skin structure integrates heterogeneous densities of 275kg/m³, 170kg/m³ and 40kg/m³ for maximum performance with minimum weight and mass. The certainly do not represent the ultimate weapon in the acoustic correction realm but do make your room quieter when positioned properly. They are also useful to reduce the devastating effects between rear vents and front wall and to address early reflections. Several colors and suede coverings give them a neat look that's easily adaptable to most interiors whether traditional or more contemporary.

In my case, the main task was to reduce the reverberation time to a more acceptable level for a room designed to accommodate high-fidelity equipment through damping on the ceiling slopes. The second critical point was the wall behind the speakers. It was both reverberant and also canceled some LF with a specific resonance mode of the plasterboard layer. To make my case more complex, it was necessary to also maintain a reflective area behind my Vivid Audio K1 speakers since they are each equipped with two rear-firing woofers. If you add the fact that the initial pre-corrected room cast surprisingly satisfactory three-dimensional images, you understand what 'walking on eggs' means.

The PYT panels allow for a gradual trial and error approach which in my case was rather pragmatic for the treatment of the front wall behind the speakers. But it could also be seen as a final touch or reinforcement for heavier acoustic treatments. I fixed these to my walls with adhesive Velcro strips. But it's also possible now to suspend the PYT panels on dedicated frames which enhances their damping characteristics through the confined air pocket between panel and wall. Effective and not at all intrusive, the PYT panel is really the simplest option I know of to start with acoustic treatment of any environment at a reasonable cost.

When the surface to be treated becomes rather large, it becomes difficult to rely solely on PYT panels without affecting the aesthetics significantly. I thus also opted for the treatment of the steep roof surfaces with a solution for professional use not from the world of recording studios but instead more public buildings and conference halls. These respect the same acoustic rules like our small private auditoriums and are concerned with the same reverberation and insulation issues. Armando Fontana from TecSArt distributes this kind of product in the so-called
Microsorber from Germany's Kaefer Company. Of course before launching into more expensive treatments relative to surface, it was necessary to measure my room's acoustic fingerprint, identify critical issues to be given priority, model the room based on geometry, the various material employed and its furniture and finally simulate various options to have a clear idea of their impact.

Commercial Microsorber installations

This measurement and analysis work was performed by TecSArt, a French audio company specialized in acoustic treatment and distribution of audio equipment. The final choice for the ceiling slopes was a double layer of Microsorber. We decided also to use a single layer for the ridge of the cathedral ceiling. Microsorber is a micro-perf polycarbonate sheet. The effectiveness of this 2mm thick material is the interaction between micro perforations and standing air on the wall. When sound waves enter the Microsorber sheet, the edge friction of the holes turns acoustic energy into heat. This undercuts reflections to significantly reduce the reverberation time. The layering of two sheets spaced 3cm apart (the first at 7cm from the wall, the second one at 10cm) increases the absorption or dissipation rate.

Three finish options are available - a simple transparent sheet, a sheet with silver print motifs and my final choice, a translucent white sheet. This can be printed with any digital picture that suits you to transform into a true decorative item. Given the large surface to be addressed, I thought it less risky to go with the natural translucent sheets. Sobriety and discretion allow these to blend completely into any environment. Affixed to the slopes, the Microsorber treatment really appeared like a second skin, giving a modern twist to the traditional structure of the wooden framework.