2 techniques
In interior spaces, there exists 2 techniques of acoustical dampening for the effective control of echo. Or more specifically, the reverberation time – the long fade of an echo.
We have the traditional technique, of materials that by their mass – thickness – absorb the energy of soundwaves.
Then we have diffusors. A whole different technique, where uneven surfaces scatter (split up) soundwaves. Which, from this surface are then reflected as many, many, smaller waves – with many, many, different paths.
Diffusers have a 2nd step that is important – as these smaller waves are about 1 meter away from having been reflected, their paths cross each-other. As these waves travel in slightly different directions, they cancel each-others energy. Effectively.
Back to the story.
Together, these 2 techniques work extremely well in treating reverberation.
Recommended alike for homes, offices and any practice of music.
Any place where vital to hear well what is spoken – of what you intend to hear. And where vital to not hear everything – and everyone.
In Finland the year 2018 was started with new regulation – a minimum standard, of maximum reverberation time. Of solutions, products, delivered to offices.
Here a short sidestep for terminology review.
An abbreviation for Reverberation time is RT60. 60dB (decibel) is the worldwide practiced level of drop of sound pressure, meaning the time from the moment where a human hears say the explosion of a balloon, until the reverberation (echo) is heard no more.
Again, back to the story.
In Finland the maximum Reverberation time for an office is now to be comparable to a bedroom level of a normal home. This is an RT60 of 0,4 to 0,6 seconds.
Concluding, looking into the crystal ball of the near future.
I am anticipating that the in-mass delivered sheets – with the small symmetrical holes – will need the efficiency of customized surfaces, of uneven profiles. At least.
Think of a bottle. A certain tone depends on the level of water, meaning the distance between surface and bottle neck. This is resonance. A diffuser panel works in a reversed process of resonance. Each ‘tower’ height – actually, well depth – equals a certain tone. A specific resonating tone.
A diffuser works in a planned frequency range. Designed through mathematical calculation. A quite wide frequency range. For example, of the human voice. Or music instrument of your choice.
Personally, I am not placing any bets on the hole-sheets with similar size of holes.
(However, they would work very well together with a sheet of absorbing material. Doubling, as the back-bone to keep the whole product structure together.)