Subject WinFlag Date Tue Jan 14 2003 11:24 Author Jon Longtin (jlongtin@ms.cc.sunysb.edu)
What is WinFlag?

	Subject WinFlag Date Wed Jan 22 2003 13:39 Author Tor Erik Vigran (vigran@tele.ntnu.no)
Unhappily there is jet not a proper link between WinMLS homepage and the Winflag homepage. Please go to the page http://wwww.WinFlag.com Hopefully this will answer your question.

	Subject WinFlag acoustical modelling Date Wed Jan 29 2003 23:19 Author Jon Longtin (pfredrick@hotmail.com)
Will WinFlag do acoustical modelling of a room? For example, if I record a dry (no reverb) voice, can I input it into WinFlag and 'hear' how the room will sound, given the acoustical treatment that I apply? If not, are there any plans to add this capability? Thanks! -Jon Longtin

	Subject Acoustical modelling Date Mon Feb 3 2003 09:57 Author Tor Erik Vigran (vigran@tele.ntnu.no)
Sorry, there are no plans to develope or to link WinFlag to any specific auralization software. WinFlag is specifically intended for the design of absorbents and you may certainly use the data for input in present room acoustical software packages as ODEON, CATT and others. Many of these packages include, as you probably know, an auralization option.

	Subject Layer Structure Date Mon Feb 17 2003 17:20 Author Karlheinz Stegmaier (mail@studioplan.de)
Hi there, will WinFlag calculate true results for the following layer structur: porous - perforated - porous without any hard wall? This would be important for the design of free standing screens.

	Subject Layer structure Date Tue Feb 18 2003 12:33 Author Tor Erik Vigran (vigran@tele.ntnu.no)
You may certainly use it for design of such a structure as long as bear in mind that the calculations applies to an infinite surface area. In fact, the program has been used to design roadside barriers with good agreement with laboratory measurements (10 sq.m area).

	Subject Modelling freely suspended abs. textiles Date Mon Feb 24 2003 12:53 Author Anders Buen (buen@bs-akustikk.no)
Hi! Is it possible with WinFlag to model the absorption in freely suspended textiles not placed in front of a wall? Regards Anders Buen, www.bs-akustikk.no

Subject Freely suspended textiles Date Tue Mar 11 2003 09:01 Author Tor Erik Vigran (vigran@tele.ntnu.no)

I take it that you want to model the the absorption capability of textiles freely hung in a room, furthermore that you presume that the sound field is diffuse. Sorry, but that is not possible with this program. However, if you know the parametres for the textile to model it as a porous material you may calculate the energi loss for each time a plane wave hits the textile surface which could be used in a reverberation model.

Subject Note on the porosity parameter Date Mon Apr 7 2003 15:22 Author Tor Erik Vigran (vigran@tele.ntnu.no) File: FLAG.dll

This note concerns the porosity parameter for two porous layer types: The Porous/Allard-Johnson model: In its present form it does not give correct answers for other porosities than near to 100%. If you intend to use this model for low porosities please download an updated version of the dynamic link library file FLAG.DLL and replace the one found in your System or System32 directory. The Porous/Mechel model: Actually, this model only applies to high porosity materials even if the porosity is a parameter. Unfortunately, this information is missing in the WinFlag manual. Mechel (the author) himself recommends setting this parameter to 95%, which he assumes applies to most commercial fibre materials.

	Subject Winflag educational/professional Date Wed May 7 2003 10:57 Author Simona Vasile (simonav27@yahoo.com)
Is it any difference between WinFlag Educational and Professional in terms of performances? Thanks

	Subject WinFlag educational/professional Date Thu May 8 2003 10:56 Author Tor Erik Vigran (vigran@tele.ntnu.no)
No, the two versions are identical. The difference in price just reflects an ordinary educational discount.

	Subject standarad values to run program Date Thu Jun 19 2003 21:54 Author jkk (hakduin@hotmail.com)
Hello, Can some one give me differentsets of standard input values to run the program effectively to learn more.especially microperforated plates backed with porous materials in different ways.Thank you.

Subject Standard values Date Tue Jun 24 2003 13:43 Author Tor Erik Vigran (vigran@tele.ntnu.no)

Could you please elaborate a little more on what you mean by standard values. Concerning porous materials it may certainly be difficult to obtain relevant data from the producer but at least you should be able to get data for the flow resistivity. As you also mention microperforate absorbers I may point out that these are normally used without any porous materials. That is the advantage of such absorbers.

	Subject Panel absorption Date Thu Jun 26 2003 10:03 Author Neil Thompson Shade, ADC, Ltd (neil@akustx.com)
Hello Prof. Vigran, Does the WinFlag software provide a method to calculate the sound absorption for freely suspended sound reflecting panels with different edge conditions (clamped or free) that might be used in a concert hall?

	Subject Absorption of freely suspended panels Date Mon Jun 30 2003 09:11 Author Tor Erik Vigran (vigran@tele.ntnu.no)
Unfortunately, calculations on finite size freely suspended absorbers are not possible with WinFlag. The only exception concerning finite size absorbers is the calculation on an absorber placed against a hard backing in a reverberation room. However, you gave me a tip on something that might be included in a later version. Thanks.

	Subject Plasterboard Specs Date Sat Jul 19 2003 01:50 Author J.C.Giner (ginerspk@uol.com.br)
Does anyone know a E- modulus, poissons number and loss factor of 1/2 plasterboard and MDF (same tick). I have been unable to find a specs above in the BRZ. Can anyone help? Reagards from Brazil

	Subject Plasterboard (gypsum board) Date Mon Jul 21 2003 12:16 Author Tor Erik Vigran (vigran@tele.ntnu.no)
The right people to supply such data must be the actual producers. I am not sure some data used for 13 mm boards here in Norway are of much use for you but here they are: Density 800 - 900 kg/m3, E-modulus: 4.1 MPa, Poissons number ~0.3 and internal loss factor ~0.06.

	Subject Sound reduction index Date Mon Sep 22 2003 12:27 Author Anders Buen (anb@bs-aksutikk.no)
Hi! How should we understand the sound reduction index that is calculated? Is it a correct understanding that the receiver room is infinite? That is the incident waves are diffuse (or a beam with given incidence angle) and the infinite test sample is a wall with an infinite space at the other side. No return of energy from the other side when there is no hard wall backing?

Subject Sound reduction index(transmission loss) Date Mon Sep 22 2003 15:32 Author Tor Erik Vigran (vigran@tele.ntnu.no)

The sound transmission loss for the combination of layers is calculated in the normal way from the tranmission coefficient, i.e. the ratio between the transmitted and the incident intensity in a plane wave at any angle with the surface. Certainly, there are infinite spaces on both sides of the specimen. The diffuse option calculates the average transmission in the range 0 - 80 degrees. The latter one you may compare with measured data from transmission rooms but be aware that the influence of a finite surface is not accounted for. Calculating the transmission with a hard wall backing has no meaning as the hard wall is infinitely stiff.

Subject Suggestion for modeling a textile Date Tue Sep 23 2003 19:02 Author Anders Buen (anb@bs-akustikk.no)

The manual and program looks very intuitive and good with references for the models and so on. I think this program is an useful tool for acoustics consultants and even producers of absorberes. Now I wonder how to model a textile in a proper manner. In the room acoustical model ODEON one may set a tranmission index in addition to the absorption factor for a material. Scenery and variable absorption is often textiles or textiles with plastic or latex backing (like Ecovelour). As the transmission index for "the first hit" may be calculated in WinFlag, I wonder if there is a suggestion for how to model a textile at least in principle. The limp mass with a proper surface mass may be given a flow resistance different from 0. Is this a proper way to model a textile? Or, e.g. a Porus model (like Mechel) may work as a "textile" if made thin enough, but then the sound insulation becomes very low. Maybe a combination would be the more correct? What would be your recommendation be for modeling a textile with a surface density of about 0.6kg/m2 and made up of wowen woull or like "Filt"

Subject On modelling textiles Date Wed Oct 1 2003 12:28 Author Tor Erik Vigran (vigran@tele.ntnu.no)

Modelling a textile may be a little tricky. If the textile has an impervious backing (e.g.plastics) I would suggest a combination of a thin porous layer and the limp mass model, the latter without any added resistance. The problem will be to estimate the flow resistivity of the porous layer. Without any measurement data you will have to make a proper guess. You may of cource use a single limp mass layer but again you must guess on the resistance value to be added. I may add that the added resistance in this model was not intended to be of a porous type. For a textile without any impervious backing a porous layer model should be used but again, without proper data on the flow resistance you are left to guess. As for comparing a model of a thin fabric with a porous layer with the same total resistance, please see the reference under the "Slotted plate" in the manual. Hopefully, this may be of some help for you. It would be interesting if there are other inputs on this question.

	Subject Calculating Rw-values Date Tue Jan 13 2004 13:39 Author Anders Buen (anb@bs-akustikk.no)
Hi! The program is efficient and useful for calculating sound reduction indexes for different constructions. However, in a new version it would be nice to get the single number Rw- value given as a separate number, if its possible. Regards Anders Buen

Subject Single number ratings Date Fri Jan 16 2004 12:37 Author Tor Erik Vigran (vigran@tele.ntnu.no)

We have been a little reluctant to include single value numbers for sound insulation, mainly because calculations are based on infinite size specimen. Size and furthermore, mechanical connections between layers may be important in practical constructions. Neglecting these factors may give unrealistic values for the sound reduction index, certainly in the higher frequency range, and may lead to misinterpretations of the calculated values of Rw. However, since the Rw – values normally are determined by the results in the lower frequency range it may be reasonable to include such a feature. Thank you for the suggestion. We certainly will reconsider our position.

Subject Sabine- and statistical absorption coefs Date Mon Jan 19 2004 12:58 Author Anders Buen (anb@bs-akustikk.no)

The program has the option to calculate the absorption coeffisient both at a given incidence angle, integrated over all incidense angles (a diffuse field) and a value from a reverberation room test, a generally higher value. 1. Now, is the absorption factor we get from the diffuse calculation the same as the statistical absorption factor? I guess the reverberation room absorption coefissient we get from the reverberation room method in the program is the Sabine abs coeff. 2. Is there a simple way to calculate the statistical abs factor from the Sabine data? Is eg. the Eyring abs factor a good guess? I guess that by measuring the flow resistivity of the porous material thus having good input data to e.g. the Mechel porous model, a relation could be found by comparing the two results from diffuse field and reverberation field calculation method. Thank you in advance! Regards Anders Buen

Subject Absorption coeffcients Date Wed Jan 21 2004 11:17 Author Tor Erik Vigran (vigran@iet.ntnu.no)

The answer to your first question is Yes, for details please see the manual, heading 5.4.1. The manual will appear using the Help menu. The result you get when using the Reverberation item is an estimate on the absorption coefficient measured on a finite sample in a standard reverberation room test, a standardized measurement procedure using the Sabine formula. I am not quite sure of what is meant by your second question. By Sabine data, do you mean reverberation time in a given room using the Sabine formula (or alternatively the Eyring formula), by which you may calculate the mean absorption coefficient?

Subject Absorption coefissients Date Wed Jan 21 2004 19:35 Author Anders Buen (anb@bs-akustikk.no)

Thank you for your answer. When measuring in a reverberation chamber the abs (Sabine) coefissient may be larger than 1. When calculating in a room acoustics software like ODEON or CATT the coefissient may not be larger than 1 of obvious reasons. I wondered if there is a short way from absorption ceofissients from reverberation chamber measurements to the absorption coefissient that can be used for large surfaces and in e.g. ODEON. I guess the correct absorption value to use in such a program is the statistical absorption coefissient. And I understand that this coefissient is not possible to measure directly. However I found the explanation in your excellent user manual, and will look in the refernce there. I understand that there is no simple way from Sabine to statistical abs factor other than using the rather complex functions as given by Thomasson for a locally reactive absorber. The simplest way would be to use WinFlag on a porous model, but I would need good resistivity data.

	Subject Absorption coefficient, wrong reference Date Wed Jan 21 2004 12:19 Author Tor Erik Vigran (vigran@iet.ntnu.no)
The reference (to the manual) in the last message should read 3.4.1. Sorry!

	Subject Absorption and transmission coefs Date Tue Feb 24 2004 11:24 Author Anders Buen (anb@bs-akustikk.no)
Is it correct to assume that the sum of the absorption-, transmsission- and reflection coeffissients should be 1? If so is it still correct to assume that the reflection coefissient equals (1-alfa - tau)^(1/2) What would be the correct interpretition? Thank you in advance!

Subject Absorption and transmission Date Wed Feb 25 2004 10:03 Author Tor Erik Vigran (vigran@iet.ntnu.no)

By definition the absorption coefficient alpha of a surface is given by the ratio of the absorbed energy to the incident energy. Either this energy is actually dissipated in or transmitted through the surface is immaterial seen from the incident side, the energy not being reflected back is by definition absorbed. For a surface of a given size the incident power Wi must be equal to the sum Wr + Wd +Wt, where the indices r, d and t indicate reflected, dissipated and transmitted power. Dividing on both sides by Wi we get 1= r + d + tau, where r, d and tau are the power reflection coefficient, a dissipation coefficient and the transmission coefficient. This may be written 1 – r = alpha = d + tau, which is the relationship you are looking for. The sound reduction index R is given by -10×lg(tau)

	Subject "Valid model space" Date Mon Mar 22 2004 13:42 Author A Buen (anb@bs-akustikk.no)
Congratulations with the new version of WinFlag! Is it possible to give recommended intervals for the input data to the models? I guess there are intervals the models work better in than others.. Thank you!

	Subject Valid range of parameters Date Wed Mar 24 2004 11:18 Author Tor Erik Vigran (vigran@iet.ntnu.no)
Giving a valid range for all parameters of the different models is extremely difficult due to the interplay of the various parameters. In version 2.0 a list of material data is included in the manual. Furthermore, new notes have been included concerning many of the parameter values. Apart from that, more information may be found in the cited references.

Subject reverberation room Date Fri Apr 16 2004 12:36 Author fadzlita (fadzlita@vlsi.eng.ukm.my)

In the sound incidence menu, I want to use the 'reverberation room' submenu. I need to know the reverberation room's volume that you used in this program because I want to compare with my actual reverberation room that I use in measurement. My reverberation room volume is 150 metercubic (minimum capacity). How the result of absorption coefficient will effect when I want to compare result between simulation using winFlag and measurement using my reverberation room?

Subject Reverberation room Date Fri Apr 16 2004 12:56 Author Tor Erik Vigran (vigran@iet.ntnu.no)

The calculation is based on the actual sound pressure distribution on a limited sample in a diffuse field, i.e. it is independent of the room volume as long as as you consider your sound field being resonably diffuse. This again means that in your measurements there is a trade-off between the room volume and the lowest frequency where the room is usable. For more information, please see the ISO standard 354. In any case, I am always interested in receiving results from such comparisons.

	Subject extra resistance correction Date Mon Apr 19 2004 11:38 Author fadzlita (fadzlita@vlsi.eng.ukm.my)
In the case of porous layer placed directly behind perforated or slotted plate, there is a possibility to add an extra resistance correction to the data, as I refer to the WinFlag manual. How should I define this parameter which take on values between zero and one? Please advise. Thanks.

Subject Resistance correction Date Mon Apr 19 2004 10:48 Author Tor Erik Vigran (vigran@iet.ntnu.no)

The resistance correction is purely empirical, partly to make up for not modelling fully the impedance seen from the hole or slit into a porous backing layer. Setting this factor equal to one you will add a resistance component to your panel equal to a thickness of one end correction of your porous material. An example: For a perforated plate the end correction is approximately 0.85 times the radius of the holes. Using holes of radius, say 4 mm, and a porous layer with flow resistivity 10 kPa×s/m2 you will add as a maximum (setting the correction equal to one) a resistance layer to your plate equal to 0.85 x 0.004 x 10000 = 34 Pa×s/m. If your experience shows that this give a better fit to measured values please feel free to change this parameter from its default value.

	Subject WinFlag reinstal Date Mon May 17 2004 16:29 Author Jan Borgers (jan_borgers@mac.com)
How can WinFlag be reinstalled after Hard Disk Error and reformatting the Hard Disk or if a new Hard Disk has to be build in. The WinFLAG 2.0.slx is still available but the Ser. No. changes after reinstall. So both WinFLAG 2.0.slx and new Ser. No. will not match. Regards Jan Borgers 2004-05-17

Subject WinFlag reinstall Date Tue May 18 2004 15:49 Author Lars H. Morset (morset@winmls.com)

If you have a hard disk crash, the WinFlag license will be lost, then please contact us about this to obtain a new unlock code. If you are going to reinstall the operative system or reformat the harddisk, first transfer the license to another PC, then transfer it back to the original PC. To find out how to transfer the license to another computer, see the section “WinFlag license and license transfer” in the help file. Best, Lars Morset

	Subject Reduct. Index of porous layer with mass Date Mon Nov 29 2004 10:09 Author Jan Borgers (jborgers@borgers-group.com)
Reduction Index of porous layer with mass. 1. layer porous 10 mm; 30 kPa s/m² (600 g/m²=60 kg/m³) 2. layer limp mass 0,2 mm; 1000 kg/m³ 3. layer porous 20 mm; 30 kPa s/m² (1200 g/m²=60 kg/m³) 4. layer thin plate 0,8 mm; 7850 g/m²; 21 GPa E-Module To calculate the effect of layer 1 - 3: where should I place the limp masses of the porous layers? Kind regards Jan Borgers 2004-11-29

Subject Reduction index of porous layers Date Wed Dec 8 2004 11:01 Author Tor Erik Vigran (vigran@iet.ntnu.no)

Do I understand you correctly when you want to include the actual mass of the porous layers in your calculations? Certainly, a porous layer will introduce a small mass loading on a connected plate and in WinFlag the modelling ignores this effect. I shall not advice you to use the limp mass layer to simulate the effect as one may overestimate it, i.e. I would compare with measured results before doing so. As for a real limp mass layer e.g. a plastic sheet, this should be placed where it is physically situated in the construction. Please report back if you have further quires.

	Subject Model Thin Flexible Plastic Sheets Date Mon Mar 28 2005 19:32 Author Neil Thompson Shade (neil@akustx.com)
Enter your message here. Hello, I looked at the materials list in WinFlag and I do not see any thin flexible plastic sheets. Is is possible to model teh absorption properties of a thin flexible sheet with a know tension that is over a fibrous layer? An application would be to calculate low-frequency tuned panels. Thank you.

Subject Flexible sheets and tuned panels Date Tue Mar 29 2005 11:32 Author Tor Erik Vigran (vigran@iet.ntnu.no)

Could you please give some further specification on the kind of plastic sheets you are concerned with, i.e. material, thickness etc. In any case, there is no possibility to introduce tension in any of the layers but in many cases designing tuned absorbers the mass of the layer is the dominating property. We have e.g. successfully modelled fibreboards backed by porous layers using the “limp mass” layer adjusting the resistance component by comparison to one measurement result. I believe this procedure is the only way to simulate the unknown resistance component due to the inherent damping of the sheets, friction along the edges, by the fastening arrangement etc. Needless to say, I shall be most interested in any results you may have.

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