You can buy 4 2X2 Gridfusors for a couple hundred bucks and play around, get a feel for the dos and don'ts of adding diffusion to your room. Small, but deep enough to be effective, EPS QRD diffusers are available from the likes of GIK. But again, properly placed relative to one another, and far enough away from you so as not to give the experience sci-fi out of phase weirdness. But I've also found it that diffusion high up, above ear level, not just behind the speakers but on the sidewalls behind the listening position, can really open up a room. They're always going to be most effective with a direct angle of incidence, so more behind your listening position than behind the speakers, unless the speakers are dipoles. But if you're too close to them or they're in the wrong place they can make the sound in the room weird and phasey. The room has basically no slap echo, but doesn't seem "dead" but I wonder if it needs some life pumped in by using diffusion.Ĭlick to expand.If you're room is 23 feet long and you're sitting far enough away from where any QRD, Skyline or other phase grate diffusers will be placed (like at least 6 feet or more), they can be amazing at making a room sound big and airy and alive. Including first reflection points on the side walls. The rest of the room has scattered absorption panels, carpet, cellular shades etc. I'm not unhappy with this setup but wonder if those two 4' tall panels, which are directly behind my speakers would be better replaced by diffraction/diffusion panels. These are free standing and located 6" away from the front wall.īass is very good in the room, much improved, and I know those central panels contribute to this significantly, though they are meant more for mids and highs. The front wall has two stacks of bass traps in the two corners, a combination of absorption panels and Vicoustic bass traps.īetween these columns there is a 4' wide x 2' tall x 6" thick absorption panel flanked by two 2' wide x 4' tall x 6" thick absorption panels. They are roughly 5 feet from the front wall. The acoustic absorption is, then, an energy dissipation phenomenon.In my dedicated 16x23 music room the speakers are on the short wall. Download a PDF of the paper titled Sound diffusion with spatiotemporally modulated acoustic metasurfaces, by Janghoon Kang and 1 other authors Download PDF Abstract:Traditional sound diffusers are quasi-random phase gratings attached to reflecting surfaces whose purpose is to augment the spatiotemporal incoherence of the acoustic field scattered from reflective surfaces. The acoustic absorption coefficient of a surface is defined as the relation between the acoustic energy that it can absorb and the incident energy that affects it.
Then, the absorbed energy turns out to be E a E i. See: CANYON EFFECT, DIFFUSE SOUND FIELD, SOUNDING BOARD. This configuration allows one to cover a large reflecting surface by periodically tiling the diffuser unit cells to cover a large area while reducing undesirable specular reflection for incident plane waves. However, the periodic arrangement of the unit cells leads to coherent constructive and destructive interference in the scattered field in some directions which is undesirable for achieving acoustic diffusivity. The spatial uniformity of acoustic energy scattered from conventional diffusers constructed in this way is a fundamental limitation of the traditional approach which is not easily overcome when one wishes to cover large reflecting surfaces.
Here’s an easy definition: diffusion is the method of spreading out sound energy with a diffusor (diffuser) for better sound in a space. In this work, we investigate spatiotemporal modulation of the surface acoustic admittance of an acoustic diffuser as a new approach to improve the sound diffusion. However, in the wide, wide world of acoustics, the sound diffusion process and tools are widely misunderstood, even by some acoustics professionals. This seems a bit odd, because it’s one of only two tools. We develop a semi-analytical model that employs Fourier series expansion to determine the scattered sound field from a surface admittance consisting of a quadratic residue diffuser (QRD) design whose individual well admittances are modulated with a traveling wave with modulation frequency, $\omega_$, and a wavenumber that matches the unit cell length, $\Lambda$. We observe significant improvement in diffusion performance due to the fact that the spatiotemporal modulation scatters sound into additional frequency-wavenumber pairs associated with harmonics of the modulation frequency and their diffraction orders. In a simple gas, we may demonstrate that the ratio between these two quantities depends basically on the collision frequency. The semi-analytical model results are verified using time-domain finite element model.
The sound speed and the diffusion coefficient are given by the following expressions. Where p p is the gas pressure, n n is the.