Is this a good way to deal with modal issues? 2. Speech Reinforcement CalculatorThe damped walls are acting as membrane absorbers below that range, requiring an additional 30-45 cm air gap, to absorb down to 20 Hz. Much ore than that (~200mm+) makes them even better at. How the Porous Media Flow Module Helps Improve Your ModelingA resonant absorber is a vibrational system that “runs” on sound pressure. Member. If velocity types of porous broadband absorbers are gonna be effective at 100Hz, they need to be about 1 meter thick which is a quarter wavelength of that frequency, or half of that thickness but with an air gap of 0. 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. Both types are effective, but whereas a resonant absorber needs to be mechanically tuned to resonate in sympathy with the frequencies being absorbed, a porous absorber does. The frictional resistance given from the material is enough to stop the wave and convert it into heat energy. g. But none with just a plaster board in front with an absorber and air gap. My ears say 'maybe' when i stick them in the front corners of a medium size room (24'x14') (7. Another important parameter of sound absorption, besides the absorbers design, is its AREA. As vibrational science will tell us a resonant absorber is a mass vibrating against a spring. Model: Allard & Champoux (1992) Absorber Parameters. If you want rear tuned absorption, build panel absorbers tuned to the lower range where the porous absorber is no longer effective. This app is designed to assist acousticians when designing environments such as home cinemas. Normal incidence. This calculator does slotted panels as. The. 45 across the frequency range. . A 2" cloud with 16800 Pa*s/m² (which should be about the value for Owens Corning 703) mounted to the ceiling (1 mm gap) absorbs less than 50% below 428 Hz and less than 25 % below 269 Hz, and practically nothing at 75 Hz. The absorber is assumed to be in front of a. Porous absorbers, as the name would suggest, are made from a multitude of tiny holes – cells, through which sound travels. s/m2 for Absorber 1, then. Figure 2-8: Typical ordered porous medium structures. Just don’t make the air gap deeper than the panel depth; a 1:1 ratio is best. -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. When I use the Porous Absorber Calculator, it shows these to be fairly similar in performance. Is the “Rigid Backed Porous Absorber” calculator not “correct” (within reasonable limits of course)?. Hey Guys, I wanted to try a few calculations of membrane absorbers to see how the different air and absorber depths affected the absorbers. Delany and Bazley. For a porous absorber backed by a rigid surface, the local reaction models give errors of less than 10% if the thickness exceeds 120 mm for a flow resistivity of 5000 Nm-4s. Porous materials, particularly polymeric foams, are the most effective sound absorbers among a wide range of existing sound-absorbing materials. 52 and download the Porous absorber calculator. Porous Absorber Calculator 4" mineral wool is actually 3. As a result, a combination of porous and membrane technologies should be able to absorb the vast majority of frequencies. Username: Password: Forgotten password? Register: 100 200 500 1000 2000 Frequency (Hz) 0 0. I know questions about this calculator have come up many times so I'm sure this topic has been covered, but there's just so much info on this forum, much of it contradictory, it's rabbit holes all the way down. But I think I have a much better understanding now, especially thanks to the Porous Absorber Calculator (the excel spreadsheet). Hello again! I have some challenges in my room, and been reading up on alot of stuff. 3. 4 0. There is also a loss in momentum due to. 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. Absorber thickness. Gear Guru . But in my design, the open area will also be roughly 50%, so I figured the results would be useful anyway. It's a big group effort and we're in the process of trying to make it easier to understand/use. When set to "Absorber", the model can be set individually for each absorber. The formulas are partly accessible and sources are clearly referred. Being made from organic stuff means nothing. Hey Avare, would love to ask you a couple questions to gain deeper insight- Quote: Originally Posted by avare ️ Corner absorbers are good at mid and high frequency absorptio. These calculators may not be very accurate, especially for more complex scenarios such as mixing materials. how to predict the behaviour of a Gobo - Gearspace. 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. Truth be told it's closer to 42Hz. how to predict the behaviour of a Gobo - Gearspace. It is assumed that there is a rigid backing (such as a solid wall) behind the. The calculation doesn't assume a sealed cavity, except for a resonator. Porous Absorber Calculator. I'm only taking axial modes into account. i think that most isolation material or foam benefit from stacking in depth and make bass trap from it. You don't need breathable cloth for bass traps. 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. The prediction of the sound absorption coefficient in diffuse field conditions is of great interest to an acoustic project. Porous materials, particularly polymeric foams, are the most effective sound absorbers among a wide range of existing sound-absorbing materials. The perforated structures are not resolved explicitly but represented by a volumetric porous zone where a volume-averaged pressure gradient in the form of a drag term is applied to. Porous Absorber Calculator BTW, if you're from Finland: I'd go with Knauf rolls of insulation from Byggmax, which amazingly is the cheapest option and among the best (if not THE best) performer for thick. For flow resistivity, look at the datasheet for your specific type of mineral wool. June 21, 2019. All in all, you don't want the air gap much. The thickness of the sound absorber was changed from d: [1. this formula or e. New Porous Absorber Calculator. Fraunhofer developed with Caruso Iso-Bond panels the VPR absorbers th. Long story short, when you have two materials, lets say one has 6kPa/m2 and another wit 12kPa/m2. Calculation models and input parameters. Calculates the absorption curve of various porous absorber systems. a superchunk) it is better to use insulation with a lower gas flow resistivity. 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. Above 60°, 5000 Pa*s/m2 is better for all frequencies. 16000, 23400, 27000 (c/o NASA!). Rs=r*d [Pas/m] When you have specific airflow resistance Rs then you can calculate air flow resistivity r for any thickness; r=Rs/d. All the source code for this app is availble on my Github repo "porous_absorber". 1 (b) is porous. at the rigid boundary, pressure maximizes while particle velocity goes to zero (thus, thin porous absorbers are not effective at LF. We, very luckily, know the density (27 kg/m3) or air flow resistivity, 12900 Nsm-4 (ISO 9053 specifies how to measure it) of the porous absorber, which is known to be well. You can predict and play around with these matters using this online calculator Porous Absorber Calculator Gas Flow Resistivity numbers (related to but not the same as density) here Common Gas Flow Resistivity numbers. Modeling the Damping Effect. A fully absorbent back wall is a fundamental of the Non Environment type of room. 2. If you didn't download it yet grab this: Porous Absorber Calculator V1. Air gap 2. Behind the template is glass fibre filling with density 6-8 lbs/ft³ (96-128. . • Absorber 2. On a microscopic scale, sound propagation in porous materials is generally difficult to study because of the complicated geometries of the frames. Wilson, simplified relaxation model. Porous Absorber Calculator. Helmholtz Absorber Calculator. 1 (a) that comprises a cavity, neck, lids and porous material. You may find it interesting to experiment with the Porous Absorber Calculator Porous Absorber Calculator V1. 4 inch absorbers have proven sound absorption values up to alpha = 0. For the sake of completeness, the technical parameters that I used for my curves: air temperature: 20 degrees Celsius, air pressure: 101325 Pa, Angle of Incidence. hi Jens, thanks for replying, from reading a few threads i see you have much more experience than I in making helmholtz absorbers. Agreement to Terms of Use This website is offered to you by acousticmodelling. 1. ReplyThe No. How the Porous Media Flow Module Helps Improve Your Modeling 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. This app is designed to assist acousticians when designing environments such as home cinemas. Multi-layer Absorber Calculator Please note that there are many factors which aren't taken into account, eg. They are usable with. On the other hand, Chris Porous Absorber Calculator actually shows that for the low. 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. s/m2 for Roxul SNS and 24,000 Pa. The lowest room mode you have between your ceiling and floor is at 75 Hz. Is it possible to predict the behaviour of a porous absorber used as a gobo somewhere in the room?. 1 Website for Pro Audio ; The No. 8 & you will see the LF absorption. 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. Porous Absorbers. I've done the modelling in Pourous Absorber Calculator, Multi Layer. Slotted Panel. Have a play with this: Porous Absorber Calculator V1. Now, I haven't been able to find any official numbers on air flow resistivity, but according to this forum post Rockwool has a flow resistivity of 9000 Pa. In base traping watch out for high absorption numbers. Adding an air gap between the. See here: Porous Absorber Calculator. The formula is: \alpha_m = A / S αm = A/S. In this study, porous packing was used. The resonant frequency could be calculated using e. 59 There are also some interesting studies from the BBC and NASA which support this approach. 58 of Porous Absorber Calculator. I'm trying to tame a huge 40Hz ringing in my room. 3. Maybe density is somewhat correlated with GFR, but to my knowledge GFR, thickness and air gap is the only thing to consider when designing Bass Traps using porous materials. Porous Absorber Calculator Preamble. The multi-layer absorber calculator is good for making "comparisons" of different proposals and to get a feel for the trends, however, you will find most pros using "actual" measurement. Impedance prediction methods have been published by Delany and Bazley, Qunli, Miki, Mechel, Mechel and Vér, Komatsu, and Allard and Champoux. doc Porous Absorber Calculator V1. For sure. This only works with absorbers of uniform thickness and triangular bass traps obviously have varying thickness. I was planning to buy the Bradford Fibretex 350 - 60kg/m3 batts (3 for $128 - 100mm thick 1200mmx 600mm). According to Delany and Bazley (and others), the speed of sound in a porous absorber is given by the angular frequency divided by the real part of the complex wavenumber. These absorber systems are called acoustic. Solving for C p gives us: C p = (C 0 *K 0) / (K p ). A 2" cloud with 16800 Pa*s/m² (which should be about the value for Owens Corning 703) mounted to the ceiling (1 mm gap) absorbs less than 50% below 428 Hz and less than 25 % below 269 Hz, and practically nothing at 75 Hz. 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. If overthinking is a. 173. 16 @ 125Hz, 0. 2 0. im using this Porous Absorber Calculator to check how the GFR would help . 055–0. and a Calculator Porous Absorber Calculator Coincidentally, I found those links another way earlier today and spent some time with them. For most of the porous absorbers the absorption coefficient α can be estimated by the very simple relation α=0. Some carefully placed spacers (smaller strips of insulation) could keep it off the wall. Resonant absorbers are further divided into panel absorbers and Helmholtz resonators. Parameter Options determine whether certain parameters appear in the Global or Absorber sections. 1. 5" rockwool on the wall (green line, absorber 2,. The absorber geometry is still cylindrical, but instead of being subdivided into two segments the cylindrical volume is subdivided into N sectors. Perforated Panel. BEHOLD THE MIGHTY POROUS ABSORBER CALCULATOR. Improved sound absorption performance of three-dimensional MPP space sound absorbers by filling with porous materials. Tuned pressure absorbers work only if pressure at tuning frequency is present, they will not work i. Each layer can be either a porous absorbent or an air gap. 8 1 Absorption Coefficient • 5000 mks rayls/m • 30000 mks rayls/mPorous Absorber Calculator V1. Joined Nov 15, 2020 Messages 7,363 Likes 7,810 Location Brussels,. 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. I don't know of anything that correctly models the valuable membrane effect. Common pa. Numerous computational models to map the acoustic effectiveness of open-porous absorbers are available for your design, for example: empirical model of. with a lot of air behind them, like about 1,2m. The measurement results serve the evaluation of the required complexity of the absorber models to be applied to model your specific materials. If perforated panel with porous absorber trap isnt the way for me to go, then what other options should I consider? Share Reply Quote. • Absorber 1 (1. 9th January 2022 #17. 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. 8 1 Absorption Coefficient • bass trap1 • bass trap2 • side panel • back panelMembrane absorbers work best with lower-frequency and bass frequencies. 2 coefficient at 50 Hz (about 0. Most bass will be absorbed by the rear wall absorber anyway; I just want something that better than nothing in the front. 2 0. Either one wants low GFR and doesn't compress, or compress as a way to emulate the higher GFR of OC 703. I'm only taking axial modes into account. They call it "k" but I'll call it Kp for clarity. They all absorb sound energy as they damp the oscillation of the air particles by friction. For example, the angle of incidence can be set as a global parameter. If you drop down to about 4K Pa. The work deals with individual parameters such as the size of the air gap; membrane absorber thickness; its density, flexibility, and, in particular, air flow resistance. Username: Password: Forgotten password? Register Porous model: Delany and Bazley (1970) Helmholtz model: Ingard/Allard. e. this incident angle is a parameter/variable that changes the effectiveness of the absorber. I am quite a noob but i’ve been researching a lot about it the past few weeks. Which one would you place closer to the wall when building a porous absorber ? Porous Absorber Calculator. As an addition I would go to Zorba and request a demo license for the program Zorba that does the same but a little different, just for checking. Tortuosity was essential a capacitance test with a wetted material. But in my design, the open area will also be roughly 50%, so I figured the results would be useful anyway. All the source code for this app is availble on my Github repo "porous_absorber". Mike Rosinski P. The WLG-045 is best for deep porous absorbers, i think about 3k rayl; about 50cm of it is the most efficient, gets you absorption down to 50Hz easily. Hi All I've recently written a porous absorber calculater for my own use and have decided to make it available over the internet. Some online calculators as well as commercial software are also available for absorption calculation. It doesn't perform as a whole system with a cavity (which isn't sealed), it's rather a velocity based absorber which. [ie 5/6 of the original air filled case] There is no design formula that I have found that allows an accurate air/porous absorber mix to be considered. The distance in mm between the perforated panel and the porous absorbent. meter. I am interested in porous absorption of low frequencies since it is. The Chris Whealy calculator can help with Helmholtz. Guitar in standard tuning only goes down to 82 hz, bass to 42 hz. CryptoApplication of Porous Metals. 58 and trying to come up with a design. You should be fine with 11 inches from the back wall to the speakers. the waterfall is ok for the resonance. If you blow air through a cloth it gets warm by friction; air flow turns into heat. Air-backed porous absorber (i. that is why many designs partially cover the bass-treatment with reflective. A microperforated panel absorber may have an absorbtion curve like this. Hi! I have an example, and I'd like to know if it I possible to do the math here. Porous Absorber Calculator. Consult with the handy "Porous Absorber Calculator" to predict your planing for a the device which won't result in a narrow band device but more of a natural low pass filter- Large perforation area+large diameter holes. DD Share Reply Quote. Porous Absorber Calculator V1. This webpage is a reimplementation of the "Porous Absorber" sheet in the above spreadsheet using Rust and Web Assembly. However we can get into the ballpark with a few simplifications. A microperforated panel absorber may have an absorbtion curve like this. 6 0. 5m thick. 922. AFAICS, the. A reset button is provided which returns all global parameters (and parameter options) to their default values. Here is the link to the Porous Absorber Calculator. To calculate the effective coefficient of thermal conductivity of porous absorbers, the simulation was carried out without air movement inside. 1 Website for Pro Audio ; The No. 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. -CSI-Spec. I'm building a 300mm deep bass trap at the front of my room and have played with the calculator at Porous Absorber Calculator and RWA45 seems to best suit my needs. For thicker absorbers and irregular slat sequences measurements are needed. There is a significant difference if one understands the concept behind porous absorption. If an absorber is composed from multiple layers of porous materials or porous materials and airspaces, the absorption coefficient can be calculated using the transmission matrix method [3], [4], [5], [6]. Porous Absorber Calculator Typical mineral wool is about 8-10K Pa. 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. . g. Porous Absorber Calculator I haven't seen great performance from the 24 inch SSC's, while the 34 inch ones rock. Absorber ParametersHi I just wanted to share an alternative design for absorbers that i made in my listening room. There are plenty of bass traps that use membranes. 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. Measuring the random incidence sound absorption coefficient (SAC) of porous materials is costly and requires a full-size reverberation room. 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. A reset button is provided which returns all global parameters (and parameter options) to their default values. Porous Absorber Calculator. Whealy C. s/m2, at which density going beyond 12" of thickness offers minimal benefit, and getting more than 50% absorption at 50Hz doesn't work. But this, this is a problem beyond simple Excel. Acoust. Presenting high surface areas to the incident sound wave provides rapid absorption of the wavefront. com, are committed to protecting and respecting your privacy and take this very seriously. 5m, you'd have to cover virtually all surfaces to reach effective absorption - your expectations are wrong It also looks like you used the multilayer porous absorber calculator (with one of the layers being a perforated panel) and not the. /s/m2 (we don't know) (according to this porous absorption calculator) Porous Absorber Calculator On the other hand a Limp. The absorber calculator tells me diffrent (pic below). It calculates the acoustic. I found Whealy's Porous Absorber Calculator and the math is beyond casual skimming and just typing it in. . 4 0. I'm using the Whealy calculator, porous absorber page. Can these be converted to Flow resistivity Pa*s/m2 ? (to be used in porous absorber calculator) Share Reply Quote. Diaphragmatic absorbers are good for going after frequencies below 90 Hz. Some things were way off. there are many, like cotton batts, fabric acoustic panels, and any porous. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between. . These porous absorber models are then used to calculate the surface impedance and absorption coefficient of different absorbents using a transfer matrix approach. The actual average sound absorption coefficient of the microperforated panel + cavity + porous metal + cavity sound absorber in the 100–1800 Hz range reached 62. 5923%, respectively. How would you calculate a triangular trap and compare different flow resistivities? Do you just pick the different depths of the triangle and look for an average?I was playing around with the Porous Absorber calculator but I don't see how to input the difference between 703 and 705. The thickness of the porous absorbent in mm. Leave a Reply Cancel Reply. The angle of incidence can be adjusted. This webpage is a reimplementation of the "Porous Absorber" sheet in the. you are inputting the incident angle of the specular energy with respect to the absorber panel. Porous Absorber Calculator. Porous Absorber Calculator. Porous absorption works by impeding. With 40cm thickness, the 040 would actually be better without airgap according to the Porous Absorber Calculator. I used the porous absorber calculator and decided that 40 cm thickness would give a good broadband absorption. Calculates the absorption curve of various porous absorber systems. Play around with the flow resistivity on a porous absorber calculator. This app is designed to assist acousticians when designing environments such as home cinemas. All. Layer 3: 240mm porous absorbent, 5000 Pa. A thought occured regarding the tuning of these panels. There is also a loss in momentum due to. Multi-layer Absorber Calculator. COMSOL Multiphysics offers. The diameter of each hole in mm (perforated panel). 8" or more. Porous Absorpton calculator says: No significant absorption for bass lower than 150 Hz: In a room with 1. (the theorical thickness is equal to the 1/4 wave length). Porous Absorber Calculator Global Parameters affect all absorbers. Like other resonance absorbers, they can be tuned to specific frequencies, but they can also be used in conjunction with porous absorbers, such as with applied foams, for broadband applications. Flow resistivity is measured with DC pressure loss. • Absorber 1. 25”x47” panel of insulation. For DIY absorber components please see: Bob Golds Fiberglass/Rockwool Absorbtion Coefficients page Absorbtion coefficents, averaged to the octave bands, do not nessessarily tell the whole story. Rigid backing. 1 Website for Pro Audio. m −2 and thickness h = 150 mm. Corner Bass Traps completely filled with Hemp (3000 rayls/m) and broadband panels 4-6" deep (maybe with membrane in the middle to prevent too much HF. For a porous absorber it assumes a rigid backing and that backing (ie the wall) is assumed to be air tight. Use the formula for the wavenumber in the porous absorber in the links I provided. You will almost certainly be sitting the Height and Width nulls, so it would be well worth trying for some. Trouble is, the only place to get it in NI is a 100 mile round trip, which I would need to do twice! A local supplier can supply rockwool cavity slab, but rockwool don't have gas. Today I did comparative measurements with. And unlike porous traps which work better. 5 rayl/m. 2 Glasull som porös dämpning" (B1. This means you can vary the angle at which the sound waves (plane waves) hit the surface of the porous absorber. 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. Users with access to the relevant academic papers. I'm willing to make it up to 0. Like other resonance absorbers, they can be tuned to specific frequencies, but they can also be used in conjunction with porous absorbers, such as with applied foams, for broadband applications. The flow resistivity of the layer in Pa. Hope you find it useful. . Diaphragm absorbers are a common tool utilized to attenuate standing waves as part of an acoustic treatment. 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. Share Reply Quote. The normal incidence sound absorption coefficient of porous materials can be predicted when the specific acoustic impedance of the material is known. Porous Absorber Calculator. Porous Absorber Calculator - Results According to the calculator, you will still get significant (I consider anything over . This calculator estimates the absorption coefficients of multi layer porous aborbers. Limp membrane, Helmholtz, or just open, all models require you to place the porous absorber at the front for maximum effect, but sometimes with a minimum air gap so it doesn't touch the front. hi guys trying to figure out which of these 2 products would be ideal for bass trapping. Here's the link: Porous Absorber. Only the mean values of the quantities involved are of practical. My Studio. This gives an open area of 18%. Actually it doesn't. Up to four absorbers can be modelled at once, each of which can have up to four layers. Close inspection reveals that the metal foam absorber plate is cooler than the. Numerous computational models to map the acoustic effectiveness of open-porous absorbers are available for your design, for example: empirical model of DELANY and. Hi there, what happens (in terms of physics and acoustics) if we have a porous absorber that is covered with a limp membrane, or rather: wrapped into a limp membrane, the membrane touching the absorber? Let us assume the membrane would have a weight of say 0. 49% of the microperforated spring steel panel absorber. abdo123 Master Contributor. These Website Terms of Use apply to the entire contents of this website under the. Your. Step 1: Cut The Wood. The distance between the holes (centre to centre) in mm (perforated panel). s/m2, a 2ft thick absorber can be 70% effective at 50Hz. The distance in mm between the perforated panel and the porous absorbent. if the absorber is larger than the wavelength (for example, 1 kHz has a wavelength of 34 cm), we can already achieve good absorption with a single absorber. s/m 2 (porous absorbent). When length of the cavity was 20 mm, average sound absorbing coefficient of the compressed and microperforated porous metal panel absorber in frequency range 100–6000 Hz reached 59. Place the cloth against the wall though, and you'll have a hard time. Porous Absorber Calculator - About. com not registered yet?I also played around with the porous absorber calculator, but in the past, real life measurements did not shine a good light on this calculator. The angle of incidence can be adjusted. Multi-layer Absorber Calculator. 2 0. Porous absorber I already have and it is not enough for my frequency. DemetrisThe No. The optimal range of key design features of the double-layer porous wave absorber as follows; submergence depth (d 1 / h) of the upmost plate is 0. Porous Absorber Calculator. As I plan to absorb also VLF at around 40 Hz I like to achieve this with very deep porous absorbers (500-1200mm). 3m x 4m). To estimate the attenuation D of silencers under practical conditions, the formula of Piening is used: D=1. 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. Running your suggested depths (70cm vs. 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. Porous materials are the most commonly used absorbers. Speech Reinforcement CalculatorNote: 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. It depends only on the pore geometry . 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. Share Reply Quote. 6 0. 6 0. Welcome to room acoustics, where good sound quality goes to die. A good thing to look at relative to bb absorbers and GFR is the porus absorber caluculator: Porous Absorber Calculator V1. Which one would you place closer to the wall when building a porous. I am using this link Porous Absorber Calculator and using a rockwool product with a 70kg/m3 density and around 30kPa. The spring is the air inside the cavity of the resonant absorber. This app is designed to assist acousticians when designing environments such as home cinemas. Multi-layer Absorber Calculator. Ye Old Porous Absorber Calculator. Absorber Parameters: Layer: This field sets the type of layer as follows: Not used; Air; Porous.