The PRD panel – a Diffusor
Traditional acoustic products work by absorbing energy. These panels work by breaking down a soundwave to multiple smaller waves, simultaneously reflecting these back into the room in multiple directions.
Thus, the first touch with a panel surface has the many waves start to cancel out each other. During their road back into the room, further cancellation is achieved.
How it works
A ‘PRD Diffusor’ panel is based on a mathematical prime number sequence. What it does, is diffuse echo. (PRD – Prime Root Diffusor)
To explain the breakage (diffusion) of a soundwave, think of throwing a stone, the size of a golf-ball, into a water. This would emit a ring of a first large wave. Imagine, a split second later, you throw the same mass but as many small rocks to hit the same place.
All of the generated small waves will almost cancel that first large wave. That is energy, dispersed. In effect, all those small rocks simulate the many standing pillars of a panel, and their different heights.
A 2-dimensional panel ‘de-fuses’ soundwaves from all directions (180* when up on a wall). A 1D panel is limited to diffuse a soundwave directly head-on.
The diffusion of a soundwave visualized :
( credits to Arqen )
For clarity, a room where both echo and noise is completely removed is called an Anechoic chamber. Loudspeaker factories have a room like this to measure a products performance. A person would experience difficulty in hearing her own voice when speaking to someone else. A quite comical situation, I can assure from my own experience.
Here we aim to control the level of cancellation. Too excessive diffusion or absorption would make a room acoustically dead.
Depending on wanted effect one may have to consider the location of the panel – in respect to the sound source and surrounding walls – or other large surfaces. As each room is individual, this may call for a customized solution.
To give you an idea of how panels may look like, please check out the Gallery.
For a better understanding, here a birds-eye view of a 3D diagram :
Diffusors are categorized by 2 types:
- the 1 dimensional QRD, and
- the 2 dimensional PRD.
PRD = Prime Root Diffusor.
QRD = Quadratic Reside Diffuser.
The main difference is that the QRD treats soundwaves coming from one geometrical plane only, whilst the PRD treats soundwaves incoming in 2 planes – X and Y planes.
In other words, a PRD treats soundwaves coming from any spot in the room.