Acoustic Absorption vs Diffusion. What is best for your room?
If you made it to this post, you are probably someone who takes good sound quality seriously. Perhaps, you have a space where you are going to install your home studio, or you want a home theater with Dolby Atmos where you can enjoy the movies you love while taking advantage of the wonderful sound of their soundtracks, audio effects, or masterful editing and mixing of those who made possible that work of art. Let’s say you look at the walls and wonder what to do so that the sound doesn’t bounce around and produce echoes and interference that will ruin your experience. Let’s say you ask Almighty Google about what to do about it, and, then, you run into a very old dichotomy in the audio industry: acoustic absorption or diffusion. That’s the question.
So, let’s start by saying that both processes exist and are used as a solution to the same problem: a sound in the chaos that we are not looking for because of a space that has not been designed for it. Improving this problem is known as acoustic conditioning: providing the optimal conditions to achieve the ideal sound by physical means, specifically by redirecting the sound waves on a surface. The point is that the solutions offered by both — absorption and diffusion — go in different directions. They are, in fact, antagonistic processes, and it is important to be aware of them in order to determine which is more appropriate in each case.
There are two important acoustic parameters in a room. On the one hand, spatiality and, on the other, the envelopment that the space itself generates. For the listener to perceive these properties ideally, it must be understood that acoustic conditioning is not just a technique for absorbing excess sound and/or mitigating reverberation in a room, although there is some truth in this. It can also be used to diffuse sound homogeneously so that the sound we emit when speaking or coming from any other object is radiated in all directions with the same intensity.
Most designers and architects set this objective as a goal, using countless resources to achieve it (let’s think of the architects who designed the amphitheaters in Ancient Greece). The truth is that the acoustic diffusion of a room can be influenced by a myriad of details as specific as the fact that the room has curtains, carpet, or the sound collides head-on with a wall. Therefore, studying in depth how to acoustically condition a room to perfection is sometimes a huge challenge.
How to find the optimal solution? Well, that depends a lot on the use given to the room since each one will have different needs. For example, in an auditorium or a music room, it is vital to have good acoustics to be able to appreciate all the nuances of sound, as well as in a theater, a conference room, or a cinema. Obviously, these rooms are of great amplitude to accommodate a large number of people, so it will be inevitable that the sound will be lost if some measures are not implemented first.
What is sound absorption? Noise, coming from one or more sound sources propagates through space in a spherical shape in all directions. When it meets or collides with a hard surface, part of the sound gets through it and a portion bounces back. The greater the mass and density of the surface on which it strikes, the greater the percentage of sound reflected, and, of course, the smaller amount of sound that passes through it. A concentration of sound is produced inside an enclosure, thus, the same sound source of equal intensity will generate much more noise inside an enclosure than if it were in a large open-air space, where there are no reflections.
All right, what is diffusion? It is the controlled displacement of sound from an area where it is highly concentrated to an area of low concentration. The sound waves are dispersed, hence the sense of localization is reduced. Normally, diffusion panels and acoustic diffusers are used to achieve this effect.
Now, absorption or diffusion? And, again: there are numerous acoustic factors to consider. There are even cases in which reducing reverberation or sound intensity level is the main objective. If, for example, we have a large room with echoes or other acoustic coloration problems, we want to correct the problem but we want to preserve the reverberation time and have all the sound energy available, the best solution will be diffusion. In concert halls, acoustic energy is a primary requirement. However, in a small theater, reading room, or home studio, it will be more important to decrease the acoustic energy in order to listen properly.
If you need professional advice for your home studio or any other room where you work with sound, do not hesitate to contact us. We can help you in the best possible way.
