3°. Parameter Options determine whether certain parameters appear in the Global or Absorber sections. Reply. 30th May 2012 #27. I'm gonna use 2 layers of these with air gap in between to get the best. The calculator in question does not take into account the mass of the porous material (that has some effect on low frequency performance due to the membrane action it might cause), only flow resistivity, and although the most important factor; the mass can sometimes affect the result quite a lot, even if the FR value is the same. A good thing to look at relative to bb absorbers and GFR is the porus absorber caluculator: Porous Absorber Calculator V1. A fully absorbent back wall is a fundamental of the Non Environment type of room. Hope you find it useful. This work presents the use of a porous-media approach for computational fluid dynamics (CFD) modelling of wave interaction with thin perforated sheets and cylinders. Example 2‑1. Limp mass material types can never achieve the proper rates of absorption that music and voice require. Porous Absorber Calculator - About. I'm only taking axial modes into account. 5" rockwool on the wall (green line, absorber 2,. Calculates the absorption curve of various porous absorber systems. Flow resistivity. com, are committed to protecting and respecting your privacy and take this very seriously. AFAICS, the absorbtion-fix is case-closed. that is why many designs partially cover the bass-treatment with reflective. Broadband absorber and gas flow resistivity. s/m 2 (porous absorbent). 500cm deep. If perforated panel with porous absorber trap isnt the way for me to go, then what other options should I consider? Share Reply Quote. hi Jens, thanks for replying, from reading a few threads i see you have much more experience than I in making helmholtz absorbers. It calculates the acoustic absorption curve of a variety of absorption devices mounted against a rigid backing such as a brick wall. Use diffrent angels because base resonances come from everywhere. com - View Single Post - Room treatment advice and help interpreting GIK's published lab results Post 16047038 -Forum for professional and amateur recording engineers to share techniques. Global Parameters affect all absorbers. However, for basic calculations relating to multi-layer porous absorbers, both calculators should give almost identical results (provided the extra options in Soundflow. The distance in mm between the porous absorbent. This gives an open area of 18%. m Shows how the open area changes the surface impedance and absorption coefficient of some Helmholtz. Porous Absorber Calculator Typical mineral wool is about 8-10K Pa. Is it possible to predict the behaviour of a porous absorber used as a gobo somewhere in the room?. Play around with the flow resistivity on a porous absorber calculator. Porous materials, particularly polymeric foams, are the most effective sound absorbers among a wide range of existing sound-absorbing materials. This webpage is a reimplementation of the "Porous Absorber" sheet in the above spreadsheet using Rust and Web Assembly. It calculates the acoustic. Absorber Parameters This calculator estimates the absorption coefficient of a porous aborbent covered with a perforated panel. Multiphysics couplings are essential to capture the effects of porous media on transport processes. I want to make my own broadband absorbers for my first reflection points. Flow resistance is the main property that sets the different types of materials apart. Obviously I'd need more surface area to make a real dent in a room that size. wooden membranes or 3. . Solving for C p gives us: C p = (C 0 *K 0) / (K p ). Impedance prediction methods have been published by Delany and Bazley, Qunli, Miki, Mechel, Mechel and Vér, Komatsu, and Allard and Champoux. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between. 922. All the source code for this app is availble on my Github repo "porous_absorber". Porous materials, particularly polymeric foams, are the most effective sound absorbers among a wide range of existing sound-absorbing materials. e. The angle of incidence can be adjusted. s/m2 There seem to be a few available on the web for common insulation materials like Rockwool but you need to hunt around for them. You can play with the porous absorber calculator to find suitable dimensions. Helmholtz Absorber Calculator. drywall membranes or 4. I need to make a keyboard macro with that sentence. Wilson, simplified relaxation model. The purpose of this blog is not to explain any of the principles of acoustics or how to interpret the data plotted on the graphs shown below, but rather to describe the architecture of a browser-based WebAssembly application written in Rust. For sure. 16000, 23400, 27000 (c/o NASA!). The normal incidence sound absorption coefficient of porous materials can be predicted when the specific acoustic impedance of the material is known. AFAICS, the. 1 Website for Pro Audio. The sound absorption coefficient calculator determines the absorption coefficient via absorbed and incident sound intensities. s Owens corning 703, Rockboard AFB (or equivalent) - 16,000 pa. This work investigates the use of hybrid double-layer microperforated panel/porous systems as wideband absorbers for applications in the closing of the test area of wind tunnels. 8 . We considered the zoy plane where the center of the tube is located as the cross-section, and obtain the cross-section of the absorber, as shown in Fig. See here for a simple porous absorber calculator. Another important parameter of sound absorption, besides the absorbers design, is its AREA. Take a look at every anechoic chamber in the world. and a Calculator Porous Absorber Calculator Coincidentally, I found those links another way earlier today and spent some time with them. Porous Absorber Calculator. 1 Website for Pro Audio. Here are some common values for absorption materials. 2m tall, 290mm deep, 47 well quadratic diffusor. I was planning to buy the Bradford Fibretex 350 - 60kg/m3 batts (3 for $128 - 100mm thick 1200mmx 600mm). If overthinking is a. When modeling porous absorbers, various empirical models are available. Air-backed porous absorber (i. 1. feet. The porous absorber calculator is accurate as far as it goes but it does not take this effect into account and therefore you usually see higher low frequency absorption in tests than the calculator predicts. OC discrepancy), 30k for 705 - I think what I have is closer to OC703, but I have a call in to Knauf to see if. doc Porous Absorber Calculator V1. a tuned membrane absorber. I've recently written a porous absorber calculater for my own use and have decided to make it available over the internet. This webpage is a reimplementation of the "Porous Absorber" sheet in the. Absorber Parameters: Layer: This field sets the type of layer as follows: Not used; Air; Porous absorbent; Limp membrane; Perforated panel; Thickness: The thickness of the layer in mm. Normal incidence. Each layer can be either a porous absorbent or an air gap. Dennis Foley says: May 4, 2023 at 5:10 pm. Porous Absorber Calculator. So the true effective depth for a gapped porous absorber is more than 1. They can be made from a variety of materials such as: acoustic foam fiberglass (glass wool) rockwool (mineral wool) And they’re extremely effective at taming common problems such as: room modes standing waves. Let’s assume a 10 cm porous absorber backed by a 10 cm air cavity, which is quite common for ceiling absorbers. For others; the diagram "B. Multi-layer Absorber Calculator 20 50 100 200 500 1000 2000 5000 10000 20000 Frequency (Hz) 0 0. sEither way, the combination or resonant and porous absorbers work very well, as the porous absorbers will cover the wet portion of your room’s acoustics while resonant absorbers will clean up the stubborn bass mess where porous absorbers may fail. Here's the link: Porous Absorber Calculator. On the other hand, Chris Porous Absorber Calculator actually shows that for the low. Results. s/m2. Most importantly, these results should match those in the papers written by the people who developed the models. Play with the porous absorber calculator. 45 across the frequency range. Porous absorbers are most effective with mid to treble tones. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between them being the absorbers. s/m2, a 2ft thick absorber can be 70% effective at 50Hz. Do you think I can rely on improved insulation in the sub area if I order the 045 Caruso (400mm) and use an airgap? Only with this airgap I would have a much better effect in the sub range. . 8 kg/m3 can be alternatives. 5 absorption coefficient at 250Hz. New Update 1. Rigid backing. Another ruff rule is, the lower the frequency, the lower the density which means, for superchunks and corner traps the WLG 045 or 040 with the thickness of min 30cm for round about 100Hz. 9615% and 73. See here: Porous Absorber Calculator. 59 We've sorta accepted that higher mass = better NRC and STC, which is generlly true compared to foam for a bass trap, but there is more to it than just. 8" or more. 1 (a) shows a typical kind of windowed volumetric solar receiver (VSR) with conventional configuration [29, 30]. Being made from organic stuff means nothing. g. Komatsu model is selectable from the porous absorber calculator's menu and is the best to use. 1) why do my. where: \alpha_m αm - The average sound absorption coefficient; For the same type of porous absorber, one with a lower bulk density has a higher total porosity, resulting in a higher sound absorption coefficient (SAC) spectrum. They are usable with. Is this a good way to deal with modal issues? 2. My comment is. A cylindrical geometry is used so that the multi-sector SeMSA. Hi All. Yeah, for porous absorbers, lower GFR is better for LF absorbtion, but the thicker the trap needs to be. What airflow resistivity number should I use in AM porous absorber calculator if I were to model 4" 4pcf Thermafiber Safing (the one carried by Menards) ? thank you 1. This was supposed to be a good alternative to 703 rigid fiberglass yet when I input 4 inches / 10cm of absorption with these figures into the calculator, the results are rather bad. An example of temperature distribution over a part of the StepRec module without air movement through the receiver is shown on Fig. 5th August 2017 #5. We’ll be building a frame that can surround a 15. For a sufficiently thick porous absorber (eg. Using a perfboard does not mean you no longer need fabric,. Similarly the BBC settled on a Panel design, again after much research. Introducing an air gap behind the porous absorber is a simple and cost-effective technique to enhance sound absorption at low frequencies. Not sure how big an absorber I'll need to reach 30hz (It may be an impossibly large box for me to build) but I think I can tackle the 55 hz one with some help. Running your suggested depths (70cm vs. I have been using the porous absorber calculator and sound flow, and have read Everest and the helmholtz part of Acoustic Absorbers and diffusers, but still have many questions. • Absorber 2. Sound absorption materials also need to have great loss of sound energy, air permeability, and refractory quality, as well as the required level of structural strength [40]. The complete way for calculating this would be to feed the data into a finite elements simulation. A microperforated panel absorber may have an absorbtion curve like this. The temperature profile is also shown in longitudinal direction in different angles for the configuration VI and the non-porous state in this igure. This means you can vary the angle at which the sound waves (plane waves) hit the surface of the porous absorber. Air is a viscous fluid, and consequently, the friction with the pore walls dissipates the sound energy. 2" wide. Ye Old Porous Absorber Calculator. s/m2, at which density going beyond 12" of thickness offers minimal benefit, and getting more than 50% absorption at 50Hz doesn't work. I decided to prepare perforated panel with porous absorber. By exciting a room mode from 2 sources with opposing phase, the corresponding peak or dip in frequency response is reduced or removed entirely. Chen, in Porous Materials, 2014 3. Reply. These calculators use algorithms which do not necessarily represent reality fully. Porous absorber. Up to four absorbers can be modelled at once, each of which can have up to four layers. Here is probably a good place to promote this relatively new Porous Absorption Calculator, thanks to Demetris. (i found URSA pureone fibre to be a good product available in my area) here is a great calculator to predict what is going to happen: Porous Absorber Calculator in acoustically small rooms like yours resulting roomresponse is probably too dry after treating the lows. . Hot links: HToM July-2015. Someone smarter than me can probably elaborate further. I would really like to do something like this for all of my panels in my studio but I can't seem to find a good material that I can easily buy in. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between. Having that much depth allows me to absorb lower but it creates. The above formula can be recursively applied to calculate the surface impedance of a multi-layered absorbent,. DemetrisThe No. 35 absorbtion at 30Hz and increase to 0. Mounting and Placement Porous Absorber Calculator Preamble. Username: Password: Forgotten password? Register home | terms of use | privacy policy | links | contact: Copyright. The main advantages of microperforated panels (MPP) as light, clean and easy-to-design sound absorbers were already established in the previous century [1,2,3]. Absorber Parameters This calculator estimates the absorption coefficient of a porous aborbent in front of a rigid backing (such as a solid wall) with an optional air gap between the absorbent and the backing. I found Whealy's Porous Absorber Calculator and the math is beyond casual skimming and just typing it in. Mass This sheet shows two absorption curves for a single layer of porous absorber with and without an air gap. Parameters Global Parameters Air temperature: 20°C Air pressure: 101325 Pa X Axis: Frequency Range: 20Hz - 10000Hz Scale: logarithmic Resolution: medium Angle of. It is particularly. 173. Another important parameter of sound absorption, besides the absorbers design, is its AREA. placed in the middle of the room. s/m2) on the flexibatts, then you can use a porous absorber calculator. 1 for IsoCal! Your handheld building acoustics calculator 👋. 49% of the microperforated spring steel panel absorber. Dammit, is it so difficult do download the bloody thing and insert some bloody numbers? OK, here are some values as being written in my secret documents (no actually derived from Porous Absorber Calculator, hehe) for 48 Hz. Porous Absorber Calculator. First, the surface porosity, defined as the ratio of the main perforation surface area to the front surface area of the absorber, is much lower than that of a conventional porous absorber. The paper is in Swedish but Colakurt as a Dane might be able to read it. g. Porous absorbers, as the name would suggest, are made from a multitude of tiny holes – cells, through which sound travels. Porous Absorber Calculator You need more advanced absorber tech in such a room combined with some good speaker technology and room adaption. Since a porous absorber, also called a velocity based absorber, works by slowing down air particles, that means that it is less effective the lower the particle velocity is. Sound-absorbing performance of copy paper composites with bulk densities below 442. A panel absorber consists of a flat panel made of wood, metal, gypsum board, or plastic material that is arranged in front of an enclosed air volume. I'm not sure on the gas flow resistance of Safe n Sound (hopefully Andre can pop in with a number tomorrow) but if its anywhere near pink fluffy, the result difference would be this: Porous Absorber Calculator - Results Now this is assuming a rigid boundary and is not taking the corner into account, but still, the difference isn't negligible. 1)4inch of OC703 floor to ceiling with an 8 inch air gap or. (broadband) the glasswool Quietel is 130kg/m^3, comes in 2400*1200*25mm sheets and costs $33. The air gap behind the absorbing material will effectively act as if the absorber would go all the way to the wall. For instance they assume a full boundary of fibre, like in an Impedance Tube. Hi! I have an example, and I'd like to know if it I possible to do the math here. First start by forming a hypothesis, something like, "The performance of broadband porous absorbers at treating room modes below 100Hz can be matched, or bettered, by narrowband helmholtz absorbers of equal or smaller size in amateur. 58 it's very clear. Glass wool fibers have poor deformation and decreased sound absorption in the. 2" wide. s/m2, a 2ft thick absorber can be 70% effective at 50Hz. 6m walls, there is a 2. Porous Absorber Calculator V1. Helmholtz Absorber Calculator. 2)12 inch of Roxul Safe N Sound Floor to ceiling. Toyoda, E. It models resistance to flow only. 4 inch absorbers have proven sound absorption values up to alpha = 0. Micro-perforated panel (MPP) absorbers have been identified as potential alternatives to traditional porous absorbers for noise attenuation in the low to the medium frequency range in many indoor applications [1,2,3]. i think that most isolation material or foam benefit from stacking in depth and make bass trap from it. The distance in mm between the perforated panel and the porous absorbent. Porous absorbers are in fact thermal materials and usually not effective sound barriers. Some carefully placed spacers (smaller strips of insulation) could keep it off the wall. 8 1 Absorption Coefficient • 5000 mks rayls/m • 30000 mks rayls/mPorous Absorber Calculator V1. perforated wood over acoustic foam porous absorbers. correct. Porous silicon carbide (SiC) is widely used as the absorber due to its high-conductivity, high-absorption, and anti-oxidation [12]. In this study, porous packing was used. -AlsoAndre, I have been messing around with some numbers with a porous absorber calculator and I seem to be getting really good results with 8" of a ~8000 Pa*s/(m^3) absorber with an 8" airgap. Let us take a look at a plane sound wave vertically incident on a rigid wall. However, not many published measurement results can be found. Porous Absorber Calculator (by Chris Whealy) ⚠️ Downloads an exel file; Various Acoustic Calculation Tools (by Chris Whealy) Drawings: 104 Broadband 4″ (10 cm) The purpose of this thread is to explain how to both physically hook up the connections between your computer and AVR/Pre-Pro to get started with REW (Room EQ Wizard) and to share information on the proper use of REW including proper techniques for both measuring and interpreting graphs, what. 58 and trying to come up with a design. Tortuosity is a measure of path length within the material. 4 0. The problem is, I'm not seeing results that confirm the general wisdom -- that. A higher fiber density leads to a more complex path inside the porous absorber therefore it implies higher interaction between sound waves and fibers. If you're interested you can find a very good spreadsheet from Chris Whealy to (theoretically) predict absorption based on "gasflow resistance" (the word you were looking for) Acoustic Calculation Tools It's the Porous Absorber Calculator file. s/m2 flow resistivity. It's a big group effort and we're in the process of trying to make it easier to understand/use. See here for a simple porous absorber calculator. The measurement results serve the evaluation of the required complexity of the absorber models to be applied to model your specific materials. I was thinking of using slats 3cm / 1. IB Sub. In any case, sorry if this is a do over. For thicker absorbers and irregular slat sequences measurements are needed. Flow resistivity: The flow resistivity of the layer in Pa. There is an excel sheet available somewhere online and also this online calculator at Porous Absorber Calculator Here's a some modeled results for 100 mm thick absorber placed at a wall using different flow. I'm willing to make it up to 0. A reset button is provided which returns all global parameters (and parameter options) to their default values. how to predict the behaviour of a Gobo - Gearspace. The materials used to fabricate the porous sound absorbers mainly involve stainless steel [62], copper. Look up the Porous Absorber Calculator and you can see the graphs for yourself. The absorber geometry is still cylindrical, but instead of being subdivided into two segments the cylindrical volume is subdivided into N sectors. Calculates the absorption curve of various porous absorber systems. 1 Review written 🎧 20 years. Which Porous Absorber to Get. F. For example, the angle of incidence can be set as a global parameter. If you put porous sound-absorbing material, processes in the system quit being adiabatic and the formula transforms into the following: fo=500/sqrt(m*d) Filling inner volume of the construction with sound-absorbing material reduces Q-value (Q) of the absorber, which leads to its working diapason extension. By the way, a 300 mm deep absorber with 100 mm thick ~15 000 rayls/m material and 200 mm air gap will provide flat absorption down to 50 Hz for practical purposes. It is generally better to fill the space keeping it about 1/2″ away from the perforated panel. Member. June 21, 2019. So I've been researching my little butt off trying to figure outSo am I getting this right? I'm trying to shoot an 85Hz null in my studio. These Website Terms of Use apply to the entire contents of this website under the. 21st March 2012 | Show parent #14. The nice absorber calculator you posted only confirms: 10cm is useless under 100Hz, 20cm does very little and more is physically impossible. Thread starter celef; Start date 2022-03-07 11:11 am; Jump to Latest celef. 6 0. Figure 7 Figure 7: The absorption of carpets varies greatly. According to the calculator, that has an absorbtion coefficient >=0. Multi-layer Absorber Calculator. 1. The first step is to calculate the volume of the room and the room surface area, which are V = 144 m 3 and S = 180 m 2,. Measuring the random incidence sound absorption coefficient (SAC) of porous materials is costly and requires a full-size reverberation room. Plugging in the numbers we already obtained: Porous Absorpton calculator says: No significant absorption for bass lower than 150 Hz: In a room with 1. , JH Brant, DanDan, Avare, can't name you all. Much ore than that (~200mm+) makes them even better at lower freq. Speech Reinforcement Calculator Note: I know that the results from Porous Absorber Calculator can't be fully applied to my design, because PAC assumes that slat width and spacing is always the same. g. Both are needed for accurate prediction of porous absorber performance. Porous Absorber Calculator. 1 (b). Bashing all other coefficients on the net IMO, it is not for every single person on this forum to know all these things unless they want to get serious about it. Absorber ParametersHi I just wanted to share an alternative design for absorbers that i made in my listening room. when using the porous absorber calculator, etc. 9 log(fd)−X. Gear Guru . When set to "Absorber", the model can be set individually for each absorber. Porous Absorber Calculator 4" mineral wool is actually 3. Diaphragm absorbers are a common tool utilized to attenuate standing waves as part of an acoustic treatment. 8 1 Absorption Coefficient • 100mm 5K • 50mm 5K, 50mm 16K • 50mm 5k, 60mm 16K, Perf PanelMicroperforated panels (MPP) are acoustic absorbers that are reclaimable, noncombustible, and environmentally friendly. You will fast get a feeling which absorber thicknes is the next one to build. Resonant absorbers are further divided into panel absorbers and Helmholtz resonators. The curve changes a bit as I vary the air flow resistivity (I'm using roughly 5000kRayls/sq. This will be against a wall, not in a corner. Either one wants low GFR and doesn't compress, or compress as a way to emulate the higher GFR of OC 703. 9 and its pore density. Single absorbers: objects such as tables, chairs, people, etc. ) broadband absorbers. 10 PPI) absorber plate was 13. This is primarily due to viscous boundary layer effects. If a different material such as rockwool or cotton or hemp fiber boards are used to make a porous absorber, you must ignore the density properties of 703 [3 lbs. Low densities seem good for broadband traps if thick enough. They have specifiable one-third-octave- center band frequencies between 40 and 100Hz. 58 (RPG´s BAD template is 600x600 mm with 512 holes, each Ø12,7 mm. The room was empty apart from a partition in one corner (usually used in office spaces). I know Jens Eklund sees Rockwool Flexibatts as an insulation material with good and appropriate air flow resistance for porous absorbers (preferably about 20 cm / 8" and thicker). But in my design, the open area will also be roughly 50%, so I figured the results would be useful anyway. Mounting and. According to the "Porous absorber calculator" spreadsheet, using a 15000 rayls/m flow resistivity, a 100mm (4") panel with a 330mm (1ft) airspace behind it (e. Rigid Backed Porous Absorber. Luca, You don't say whether you want corner bass traps, membrane absorbers or Helmholtz resonators. s/m2. I thought tri (superchunk) style absorbers were good for low frequencies mainly? Quote: Originally Posted by avare As practical proof, consider how often people have. So, when guys like me and the OVERWHELMING MAJORITY of people on these forums who are looking for acoustic. That material still needs to be breathable. Gapped porous absorbers are used in thousands of spaces with gap to depth ratios up to 20:1. e. Let's call C p the speed of sound in the porous absorber. Place the cloth against the wall though, and you'll have a hard time. Perforated Panel. 20 per sq metre the Fibertex 350 is 60kg/m^3, comes in 1500*900*50mm sheets and is $20. Helmholtz Absorber Calculator. s values: Pink R-30 insulation - 4000 pa. For example, I want to absorb. The No. Username: Password: Forgotten password? Register Porous model: Delany and Bazley (1970) Helmholtz model: Ingard/Allard. (notice the. Leave the 3" gap between the insulation and wall to move the mass out towards where lower frequencies will have some velocity instead of pressure (Porous Absorber Calculator) which is what we're targeting here. 59 Play around with with 6 kpa equal to 6000 rayls. Congyun and Qibai (2005) calculated the acoustic impedance for multi-layer absorbers such as perforated plates and air space or perforated plates and porous materials by using an iterative method. These briefly and simply cover the basics (and have lots of pictures ). A microperforated panel absorber may have an absorbtion curve like this. Diaphragmatic absorbers are good for going after frequencies below 90 Hz. by any material. I'm playing around with porous absorber calculator and trying to find a good balance between effective and practical. Air-backed porous absorber (i. A reset button is provided which returns all global parameters (and parameter options) to their default. but do consider the reality it's a little bit better than the plot because the calculator considers only a single angle of incidence. Foams and granular materials like porous. A ruff rule is the porous absorber should have at least the thickness of 1/3 of the wavelength you like to absorb. The absorber calculator tells me diffrent (pic below). The actual average sound absorption coefficient of the microperforated panel + cavity + porous metal + cavity sound absorber in the 100–1800 Hz range reached 62. It is assumed that there is a rigid backing (such as a solid wall) behind the. ↑ top; home; New Product Alert; classifieds; reviews; deal zoneThe distance between the holes (centre to centre) in mm. COMSOL Multiphysics offers. Absorber thickness. Above 60°, 5000 Pa*s/m2 is better for all frequencies. 2. 2 0. 5th August 2017 #5. s/m2 for Absorber 1, then. Absorber thickness. Which one would you place closer to the wall when building a porous. Parameters Global Parameters Air temperature: 20°C Air pressure: 101325 Pa X Axis: Frequency Range: 20Hz - 10000Hz Scale: logarithmic Resolution: medium Angle of incidence: 0° Porous model: Komatsu (2008) Helmholtz model: Ingard/Allard Absorber Parameters • Absorber 1 20mm Slotted Panel, 10mm/80mm (12. PaulRain. First of all, I came across the Porous Absorber Calculator by Chris Whealy. 4 The Superchunks in the Absorption test at studiotips. 1. I was thinking of using slats 3cm / 1. These absorber systems are called acoustic. Behind the template is glass fibre filling with density 6-8 lbs/ft³ (96-128. this online calculator b) A bass or broadband absorber using porous material with a perforated plate or slats in front which is a different system. This only works with absorbers of uniform thickness and triangular bass traps obviously have varying thickness. with porous absorber assuming you use the good GFR and good surface, you will need a tickness equal at 2,8 m/ 111 inch for maximum absorbtion. im using this Porous Absorber Calculator to check how the GFR would help . Mathematical models have been developed to evaluate the dynamic behavior of two solar air collectors: the first one is equipped with a V-porous absorber and the second one with a U-corrugated absorber. Your. I used theIve been experimenting with the Porous Absorber Calculator V1. But the problem of two calculators showing different result could be related to a formula that does not include the difference between an air gap and. If you are making standard porous absorbers and were trying to target say 50Hz even a 1 meter thick trap is not very efficient at that frequency IF the density is 45Kg/m3 and this material has a GFR of 14755Pa. (the blue and red are OC703). The lowest room mode you have between your ceiling and floor is at 75 Hz. 15 at 40 Hz), which I'm guessing isn't amazing. Layer 3: 240mm porous absorbent, 5000 Pa. Another theoretical test case was made by adding an air cavity to the soft porous absorber, leading to flow resistivity σ = 10 kPa. Even if it's peaked in planned location, most probably you'll have to measure and investigate to see results. They all absorb sound energy as they damp the oscillation of the air particles by friction. The multilayer absorber was composed of an MPP and three additional layers, consisting of polyurethane (PU) foam, jute felt, and an air gap. If you blow air through a cloth it gets warm by friction; air flow turns into heat. The flow resistivity of the porous absorbent in Pa.