Resonance absorbers, also known as tuned traps, pressure absorbers, or narrowband absorbers, are devices that are frequency-dependent. This is because of the desired resonance of a particular material at a specific wavelength. There are several types of resonance absorbers. Some examples are the Jaumann absorber, the Salsbury screen, and the Dallenbach layer. In addition, there are also the circuit analog absorbers and the crossed grating absorbers.
Resonance Absorbers: the Physics
This kind of absorbers involve either a mechanical or an acoustic oscillation system. This system is commonly a membrane absorber featuring a solid plate with a tight air space on the rear end. Within membrane absorbers, the absorption achieves its maximum value when reaching a specific resonance frequency. They are capable of falling to lower values at both higher frequencies and lower frequencies as well.
How to Employ Them
Users can control this maximum value of absorption by choosing a specific material to fill the air space. Sound engineers often fill the space with porous material to broaden the absorption over the range of the frequency. This material can be either a porous board or blanket made of mineral or glass fibers. The value of absorption depends entirely on the flow resistance of the particular material. In other words, it doesn’t depend on the depth of the airspace, the open area, the perforation diameter, or other physical dimensions of the sound absorptive treatment.
Why Choose Resonance Absorbers?
On the one hand, resonant absorbers zero in on specific problems with bass frequencies while ignoring everything in the mid/upper range. On the other, porous absorption provides great broadband coverage and lacks bass absorption. Also, the first operate best when placed against a wall. The reason is that the pressure tends to be higher and the sound waves are more likely to collide. In contrast, porous traps work better when spaced of the wall so they require much more space than resonance absorbers.
If you want to learn more…
Other kinds of soundproofing devices are available to you in our site. You can learn from acoustic boards, fiberglass, or foam, for instance. Additionally, you can consult what reflection filters, ceiling clouds, and the Helmholtz Resonator are all about.