For example, the angle of incidence can be set as a global parameter. Both are needed for accurate prediction of porous absorber performance. Porous Absorber Calculator Global Parameters affect all absorbers. (the theorical thickness is equal to the 1/4 wave length). Helmholtz Absorber Calculator. Hey guys, I need broadband absorption down to 50Hz. Chen, in Porous Materials, 2014 3. 5th August 2017 #5. what is your opinion about porous absorber calculators online such as: and. DanDan, Regarding your remarks on ratio of absorbent to air gap for the 6" depth I have available to me (2" absorb+4" air vs. All the source code for this app is availble on my Github repo "porous_absorber". Porous Absorber Calculator. Porous Absorber Calculator tlindaas, did you, will you, or may I, repeat the content of this post over in the GFR gathering thread? Common Gas Flow Resistivity numbers. 2m porous absorber,. In this study, porous packing was used. This was measured and also predicted in Ethan's room mode calulator for thePorous absorbers need considerable thickness to maximize the absorption performance at low frequencies since the minimum thickness required is usually one order of magnitude smaller than the. g. 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. Air is a viscous fluid, and consequently, the friction with the pore walls dissipates the sound energy. s/m2 flow resistivity. I've been playing with the Porous Absorption Calculator a lot and am perfectly happy with the level of low freq. Hello ! First post but i'm reading for years Thank to everybody who shares so much great info ! ( Thomas Northward, Boggy, GE, Jens E. how to predict the behaviour of a Gobo - Gearspace. Width of hangers is used to define lowest frequency, membrane absorbers isn't included in this simple model/formula, and 1. The ZORBA software is a tool for calculating the sound absorption coefficient of porous materials and perforated surfaces. 16 @ 125Hz, 0. ↑ top; home; New Product Alert; classifieds; reviews; deal zoneThe rectangular version is easier to build and saves material. 69%, which was superior to that 25. Look at the densities. Flow resistivity. This may be an old thread, but the problems with the slotted panel graph still persist in the latest version 1. (to be used in porous absorber calculator) Share Reply Quote. s/m2. AFAICS, the. The composite sound absorber includes a MPP (micro-perforated panel) layer, a porous material layer, and an air cavity layer. i think that most isolation material or foam benefit from stacking in depth and make bass trap from it. 5 absorption coefficient at 250Hz. Standard pink fluffy is ~5,000. So attempts to calculate or predict absorption using a calculator based on a single depth are futile. 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. ↑ top; home; New Product Alert; classifieds; reviews; deal zoneAt high frequencies, i. The thickness of the porous absorbent in mm. Mass This sheet shows two absorption curves for a single layer of porous absorber with and without an air gap. Absorber Parameters: Layer: This field sets the type of layer as follows: Not used; Air; Porous. Porous absorbers are most effective with mid to treble tones. The calculators can save you from having to tear stuff out that is worse than it was: Porous Absorber Calculator V1. Absorber ParametersHi I just wanted to share an alternative design for absorbers that i made in my listening room. 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. Porous Absorber Calculator. IB Sub. Often porous materials with spherical grains have lower porosity than materials composed of non-spherical grain. 4 0. We can ignore the imaginary term in the equation. Porous materials, particularly polymeric foams, are the most effective sound absorbers among a wide range of existing sound-absorbing materials. Look up the Porous Absorber Calculator and you can see the graphs for yourself. Damping is generally achieved by a combination of three processes: resonances that trap the acoustic energy at given frequencies, absorption of acoustic energy by different porous and fibrous lining materials, and losses in perforated plates, also known as perforates. Username: Password: Forgotten password? Register: We, acousticmodelling. A fully absorbent back wall is a fundamental of the Non Environment type of room. According to the calculator, that has an absorbtion coefficient >=0. With a two foot thick area, you have the possibility of getting significant absorption at 40 Hz. Let us take a look at a plane sound wave vertically incident on a rigid wall. See below for approximations of absorption coefficients for the theoretical 21" thick R38 (blue line, absorber 1) and the 1. ZORBA is currently available in version v3. Some things were way off. more absorber+less gap), I seem to be coming to a different conclusion. Some things were way off. 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. They call it "k" but I'll call it Kp for clarity. In order to optimize sound absorption, it was generally advised to predict and calculate the absorption based on the dependent parameters and optimize the parameters to obtain the desired absorption. Perforated Panel. Comparision: Porous Absorber Calculator - Results In this math example, Sonorock actually goes lower in terms of absorption than Basotect. Each 6x3 roll of BassBloc™ Bass Absorber covers an area of 18 sqft : BEST FOR SOUND AND BASS ABSORPTION: BassBloc™ Bass Absorber Acoustic Foam. - Room modes calculator home | terms of use | privacy policy | links | contact: Copyright © acousticmodelling. Porous Absorber Calculator 4" mineral wool is actually 3. In any case, sorry if this is a do over. Thus, an MPPA layer with an attached porous material layer in front of an airgap makes the MPPA absorber more. Your bass and mid-bass will depend heavily on location, and the only cure is multiple subwoofers, and good acoustic treatment. The distance between the holes (centre to centre) in mm (perforated panel). The LSA proposed in this paper is shown in Fig. Been playing with the perforated panel/Helmholtz part of the porous absorber calculator spreadsheet. Compared to porous absorption, which offers great broadband coverage but often lacks in bass absorption…Resonant absorbers (aka tuned traps, aka narrowband absorbers) essentially do the opposite…by zeroing-in on specific problems with bass frequencies, while ignoring everything in the mid/upper range. 15 at 40 Hz), which I'm guessing isn't amazing. This app is designed to assist acousticians when designing environments such as home cinemas. But in my design, the open area will also be roughly 50%, so I figured the results would be useful anyway. The porosity of copper foam is 0. All formulas and units are the same in NASA. ReplyThe No. It calculates the acoustic absorption curve of a variety of absorption devices mounted against a rigid backing such as a brick wall. Forum Donor. Having that much depth allows me to absorb lower but it creates. diffusors depending on geometry plus a minimum of porous absorbers behind thin (5. But none with just a plaster. 1 Review written 🎧 10 yearsPanel absorbers are yet another form of resonant oscillating mass-spring systems. 5 m for the porous absorber to hit the quarter wavelength. The second porous absorber represents a more dense material and is labelled ‘hard porous’, with a flow resistivity σ = 30 kPa. They have minimal success with lower and bass. 35 per sq metre here are some specs for the products. 1 Website for Pro Audio. The absorption is very dependent on the type of carpet and how it is made. com, are committed to protecting and respecting your privacy and take this very seriously. 55 Normal fluffy is about 5000 rayls/m with denser fibreboard around 15000-25000. m for pink fluffy, 8000-1000 for Safe and Sound, 16. My questions are: 1. COMSOL Multiphysics offers. This webpage is a reimplementation of the "Porous Absorber" sheet in the above spreadsheet using Rust and Web Assembly. Guitar in standard tuning only goes down to 82 hz, bass to 42 hz. So the true effective depth for a gapped porous absorber is more than 1. 3m x 4m). This calculator does slotted panels as. . at the rigid boundary, pressure maximizes while particle velocity goes to zero (thus, thin porous absorbers are not effective at LF. . 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. 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 webpage is a reimplementation of the "Porous Absorber" sheet in the above spreadsheet using Rust and Web Assembly. Goes up to 170/KG/M3. I am using this link Porous Absorber Calculator and using a rockwool product with a 70kg/m3 density and around 30kPa. A porous absorber is any kind of porous or fibrous material such as textiles, fleece, carpets, foams, mineral wool, cotton wool and special acoustic plasters. The angle of incidence can be adjusted. This calculator estimates the absorption coefficients of multi layer porous aborbers. Joined 2012. plastic membranes or 2. If perforated panel with porous absorber trap isnt the way for me to go, then what other options should I consider? Share Reply Quote. This only works with absorbers of uniform thickness and triangular bass traps obviously have varying thickness. BEHOLD THE MIGHTY POROUS ABSORBER CALCULATOR. With 40cm thickness, the 040 would actually be better without airgap according to the Porous Absorber Calculator. June 21, 2019. Just don’t make the air gap deeper than the panel depth; a 1:1 ratio is best. 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. Some online calculators as well as commercial software are also available for absorption calculation. The Porous APorous Absorber Calculator Sent from my iPhone using Tapatalk. Above 60°, 5000 Pa*s/m2 is better for all frequencies. Leave a Reply Cancel Reply. Thickness of the template is 1/8” = 3,175 mm. 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. drywall membranes or 4. Room modes mess up everything below about 300Hz. Fraunhofer developed with Caruso Iso-Bond panels the VPR absorbers th. We measure the total room sound absorption in sabins. Long story short, when you have two materials, lets say one has 6kPa/m2 and another wit 12kPa/m2. Absorbtion figures for perforated panels with absorber behind,. • Absorber 2. 30th May 2012 #27. Calculates the absorption curve of various porous absorber systems. s/m2. "f" is frequency (50 Hz in this case), "σ" is flow resistance. s/m2) on the flexibatts, then you can use a porous absorber calculator. Hi All I've recently written a porous absorber calculater for my own use and have decided to make it available over the internet. 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. Hot links: HToM July-2015. s/m 2 (porous absorbent). Wilson, simplified relaxation model. 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. concepts, models, and algorithms developed for porous media in the geosciences are not directly applicable and there is a very strong need for tailored models. 21st March 2012 | Show parent #14. Foams and granular materials like porous. 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. abdo123 Master Contributor. The measurement results serve the evaluation of the required complexity of the absorber models to be applied to model your specific materials. The flow resistivity of the porous absorbent in Pa. 8 1 Absorption Coefficient • 5000 mks rayls/m • 30000 mks rayls/mPorous Absorber Calculator V1. 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. A microperforated panel absorber may have an absorbtion curve like this. Each layer can be either a porous absorbent or an air gap. 6 0. 's most successful trap, after many many attempts, was a panel one. Presenting high surface areas to the incident sound wave provides rapid absorption of the wavefront. I want to make my own broadband absorbers for my first reflection points. 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. The available calculators allow you to see the impact of this absorber on the absorbers frequency response for different depths and spacings. You should be fine with 11 inches from the back wall to the speakers. and the porous material layer was established by using Delany and Bazley’s model. Hope you find it useful. . Its value ranges from 0 to 1, with 1 being the perfect absorber. The pancake absorbers are different from conventional porous materials in two respects. These panels are. Since membrane absorbers require high level of precision to perform at the desired frequency, they are often customized for a specific application. 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. 59 Here is another: Porous Absorber Calculator The trick seems to be finding the Flow Resistivity for the material you want to use: Pa. Helmholtz Absorber Calculator. 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. Depends on density of material. V-corrugated absorbers have been. 4 0. Measuring the random incidence sound absorption coefficient (SAC) of porous materials is costly and requires a full-size reverberation room. The curve changes a bit as I vary the air flow resistivity (I'm using roughly 5000kRayls/sq. Furthermore, if you have a look at Chris Whealy's Porous Absorber Calculator and plug the numbers for the frequency range of absorption for regular fiberglass batt insulation (R-13) @ about 8000 rayls/m compared to 60kg rock wool @ about 22000 rayls/m. I believe that it's working correctly and is stable but would appreciate some feedback if you have any problems with it. Porous Absorber Calculator. . Calculation models and input parameters. The multilayer absorber was composed of an MPP and three additional layers, consisting of polyurethane (PU) foam, jute felt, and an air gap. m Shows how the open area changes the surface impedance and absorption coefficient of some Helmholtz. ( this is mBuy Kinsler & Frey "Fundamentals of Acoustics" 2nd edition, look up how the boundary impedance of such an arrangement is calculated based on the Delaney-Bazley theory for porous absorbers, calculate the reflection coefficient for normal incidence, and vary the flow resistivity to minimise the reflection coefficient for a given arrangement. 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. If overthinking is a. 3. 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. If you blow air through a cloth it gets warm by friction; air flow turns into heat. This webpage is a reimplementation of the "Porous Absorber" sheet in the above spreadsheet using Rust and Web Assembly. Your key says they are all rigid porous absorbers. 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. 8 & you will see the LF absorption. F. These briefly and simply cover the basics (and have lots of pictures ). Multi-layer Absorber Calculator 20 50 100 200 500 1000 2000 5000 10000 20000 Frequency (Hz) 0 0. The Whealey porous absorber calculator tells you all: Number one, make them thick, number two alternatively use an air gap, number three, don't make them too dense (see my posts in the link above for a rough understanding of that). Parameter Options determine whether certain parameters appear in the Global or Absorber sections. Even 20cm with 20cm air gap will not result in considerable reduction around that peak. Most bass will be absorbed by the rear wall absorber anyway; I just want something that better than nothing in the front. 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. 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. 1. Being made from organic stuff means nothing. 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. Komatsu model is selectable from the porous absorber calculator's menu and is the best to use. Appl. . Mechel and Ggrundmann. The mass per unit area in Kg/m 2 (limp membrane). 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. C0 is the speed of sound in air, which we'll say is 343 m/s. • Absorber 1. 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. For 60 cm the situation is similar, though with different frequency and angle values. Global Parameters affect all absorbers. - the area covered with the absorbers is not large enough (you mention 36Hz, which is a wave of 9. It calculates the acoustic absorption curve of a variety of absorption devices mounted against a rigid backing such as a brick wall. Documentation. Jens. Thermohanf porous absorbers. 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. Porous Absorber Calculator - Results According to the calculator, you will still get significant (I consider anything over . 1 Website for Pro Audio. with a lot of air behind them, like about 1,2m. this incident angle is a parameter/variable that changes the effectiveness of the absorber. 90 width you are lost in regards to bass if you rely on absorption only. The mass is the cabinet and front wall or diaphragm. In this analysis, porous absorbers with 20,000 Ns/m 4 flow resistivity was used. 4 kg/m3 and corrugated board composites with densities of less than 474. Each layer can be either a porous absorbent or an air gap. Glass wool fibers have poor deformation and decreased sound absorption in the. As vibrational science will tell us a resonant absorber is a mass vibrating against a spring. Now note that the following must also be true (I'll leave aside for the moment why it must be true): K 0 /K p = C p /C 0. Absorption Area. 2 0. I've done the modelling in Pourous Absorber Calculator, Multi Layer. A porous absorber may have an absorbtion curve like this. 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. 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. Porous absorbers, as the name would suggest, are made from a multitude of tiny holes – cells, through which sound travels. Although porous and fibrous materials provide satisfactory sound absorption in many noise control applications, they can produce particle discharge, which can discourage. Even if it's peaked in planned location, most probably you'll have to measure and investigate to see results. per cubic foot] and instead seek a material with similar gas flow and impedance properties in order to match performance with 703. Multi-layer Absorber Calculator. However we can get into the ballpark with a few simplifications. If you want rear tuned absorption, build panel absorbers tuned to the lower range where the porous absorber is no longer effective. When set to "Absorber", the model can be set individually for each absorber. The actual average sound absorption coefficient of the microperforated panel + cavity + porous metal + cavity sound absorber in the 100–1800 Hz range reached 62. 58 and trying to come up with a design. There is also a loss in momentum due to. Thread starter celef; Start date 2022-03-07 11:11 am; Jump to Latest celef. Porous Absorber Calculator. 50%) 400mm Porous Absorbent, 4000 Pa. 59. Try this calculator: Porous Absorber Calculator Generally, the thinner the absorber, the higher the resistivity needs to be. The air gap behind the absorbing material will effectively act as if the absorber would go all the way to the wall. Using the porous absorber tube causes the surface temperature to decrease. and a Calculator Porous Absorber Calculator Coincidentally, I found those links another way earlier today and spent some time with them. A thought occured regarding the tuning of these panels. 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. Porous Absorber Calculator. And unlike porous traps which work better. Can these be converted to Flow resistivity Pa*s/m2 ? (to be used in porous absorber calculator) Share Reply Quote. -CSI-Spec. s values: Pink R-30 insulation - 4000 pa. These absorber systems are called acoustic. Porous Absorber Calculator 2) the filtered impulse response at -60 dB or the topt can give an indication. How the Porous Media Flow Module Helps Improve Your ModelingA resonant absorber is a vibrational system that “runs” on sound pressure. g. Porous Absorber Calculator Preamble. Which one would you place closer to the wall when building a porous absorber ? Porous Absorber Calculator. Coates and Kierzkowski in their paper describe the advantages of thin, light membranes that can replace traditional bulky and economically disadvantageous porous absorbers. A higher fiber density leads to a more complex path inside the porous absorber therefore it implies higher interaction between sound waves and fibers. Username: Password: Forgotten password? Register home | terms of use | privacy policy | links | contact: Copyright. . 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. They achieve a high- absorption coefficient, utilizing a relatively small volume. Ye Old Porous Absorber Calculator. Abstract. Hi All. You don't need breathable cloth for bass traps. Helmholtz Absorber Calculator. Maybe with tuned absorbers or perforated panels, but there are others here that have more experience with that. Slotted Panel. Much ore than that (~200mm+) makes them even better at. Multi-layer absorbers composed of perforated plates, airspaces or porous materials are used widely to absorb broadband noise [1], [2]. s/m2 for OC703 (Please let me know if these are incorrect). 1 Website for Pro Audio ; The No. Porous Absorber Calculator I haven't seen great performance from the 24 inch SSC's, while the 34 inch ones rock. 30th October 2014 #2. The calculation doesn't assume a sealed cavity, except for a resonator. The collectors have the same geometry, cross-section surface area and are built from the same materials, the only difference between. It also depends on which bass frequencies are problematic in your room. The diameter of each hole in mm (perforated panel). e. There are generally two types of bass traps: resonant absorbers and porous absorbers. All the source code for this app is availble on my Github repo "porous_absorber". online calculators for porous absorbers. m −2 , thickness h = 50 mm, and cavity depth. I am currently trying to design a slotted panel with a resonant frequency of 133 Hz and I really need to know if I can use PAC at all. My Studio. A reset button is provided which returns all global parameters (and parameter options) to their default values. There is also a loss in momentum due to. 117–0. In contrast, a 300mm chunk with zero. s/m2, at which density going beyond 12" of thickness offers minimal benefit, and getting more than 50% absorption at 50Hz doesn't work. Flow resistance is the main property that sets the different types of materials apart. 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. 52 and download the Porous absorber calculator. Play a little bit with different thickness and different Flow Resistivity you will see your self. Porous Absorber Calculator. The particle velocity is at maximum at 90° and 270° (Vmax) and minimum at. meter. Note the ISD gap of such rooms is very long, infinite perhaps. Global Parameters: Air temperature °C. Served on a. 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. Have a look at what happens with 100mm panels AND a 50mm air gap though just out of curiosity, and also see what happens with a 100mm air gap: Porous Absorber Calculator - Results Well worth pulling them out as much as you can, up to their own depth or a bit more. The distance in mm between the perforated panel and the porous absorbent. For sure. Helmholtz Absorber Calculator. Porous Absorber Calculator. Solving for C p gives us: C p = (C 0 *K 0) / (K p ). Select frequency range : 20 - 300 Hz. Delany and Bazley. Average sound absorption coefficient formula. 0 with a German user interface and is developed by Marshall Day Acoustics. (broadband) the glasswool Quietel is 130kg/m^3, comes in 2400*1200*25mm sheets and costs $33. 9, 10,. Tortuosity is a measure of path length within the material. I previously made some cube shaped 30 cm deep blocks, which my wife was not too fond of, so when i needed some absorbers for treatment of 1st refleksions I went with this circular design, which my wife is actually quite happy with. 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. The distance in mm between the perforated panel and the porous absorbent. These Website Terms of Use apply to the entire contents of this website under the. BTW, I prefer the Komatsu model over the default model of the online calculator. Porous Absorber Calculator Typical mineral wool is about 8-10K Pa. They are usable with. s/m 2 (porous absorbent). the direct path angle/evctor is irrelevant. Porous Absorber Calculator V1. 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. Being a porous absorbent, carpet produces mid– and high–frequency absorption. . The room was empty apart from a partition in one corner (usually used in office spaces). 3. The mesh part shown in Fig. The porous absorber calculator does not offer a complete solution for diagonal traps. 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. 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. Another important parameter of sound absorption, besides the absorbers design, is its AREA. However, for basic calculations relating to multi-layer porous absorbers, both calculators should give almost identical results (provided the extra options in Soundflow are not used). 703 and other 48KG materials, have been tested and show to perform extremely well in the bigger SuperChunks, down to 35Hz in one instance. 0 with a German user interface and is developed by Marshall Day Acoustics.