A: When calculating Speech Transmission Index in Odeon you need to type in a total background noise level, which you type into the room setup. Below video shows how you can use sources in Odeon to find this total background noise level.

A: First consider if the reverberation time is the best parameter to use. E.g. DL₂ could be a better parameter for a larger room. Simulating reverberation time in a point response calculation in Odeon, corresponds to measuring the reverberation time. Therefore refer to a measuring standard e.g. ISO 3382. Make sure that you use only one Omni-directional source for each calculation job. In large rooms it is important to have sufficient distance between source and receivers, receivers should not be placed in the near field of the source but in the reverberant far field characterizing the room. ISO 3382-2 includes an equation describing the recommended minimum distance between source and receiver:


Where: V - is the Volume in cubic meters; C - is the speed of sound in meter/second and ^{^}T - is the expected reverberation time in seconds.

Furthermore it is a good idea to use a larger number of source receiver pairs in large rooms than the measurements standard demands, to cover the larger area.

If the room consists of many coupled or unregular areas with different properties, it will may not be possible to find one reverberation time that characterizes the room and we advise you to supplement the reverberation time with analyses of STI, SPL, EDT, DL2 and auralisations in different areas.

A: The Strength G (as defined in ISO 3382) is the same as the SPL if:

- One (and only one) omni-directional sound source is turned on, and
- the overall gain in the point source editor is set to 31 dB.

In this case the bottom line in the point source editor will display a value of 0 dB for the SPL on axis at 10 m. This is exactly the reference of the Strength, G. So, all calculated SPL results are actually also G values.

However, in all tables and graphs you will only find the symbol SPL, even when the conditions for G are fulfilled.

A: First a general comment on how the reverberation time is calculated from the impulse response. ODEON follows closely the ISO 3382 standard for measurements, i.e. the T30 parameter is found from the slope of a linear regression line that follows the decay curve from -5 dB to -35 dB. In any room the decay curve is a mix of 1-, 2-, and 3-dimensional modes, and generally they have different decays, i.e. the total resulting decay curve is not a straight line, but can be more or less bent. (The 1-dimensional modes have typically the longer reverberation time, and the 3-dimensional modes have the shorter reverberation time).

When the ceiling absorption is high and the walls are reflecting this can give a strong one- and two-dimensional horizontal reverberation. When making the ceiling even more absorbing it means that the one- and two-dimensional sound field gets relatively stronger, and so the reverberation time gets longer. Normally the sound pressure level will decrease. Therefore we recommend that you use auralisation and other acoustical parameters, e.g. STI, SPL and for large rooms DL2 to analyze the acoustics.

 Claus Lynge Christensen, Gry Bælum Nielsen, Jens Holger Rindel, "Danish Acoustical Society Round Robin on
room acoustic computer modelling". ODEON A/S, 2008. 20 pages.

A: Make sure source and receiver has mutual distance between them of 0.9 to 1.1 m

A: For calculation of STI with a certain Signal/noise ratio, calculate the SPL in your receiver point (read result in Energy parameters in Single Point Response). Then set the background noise to this level +/- your background noise SNR. Then when you calculate the Point response again, the STI is calculated with the desired background noise.

When making an auralisation with the same S/N – it is more complicated among things because the signals used for auralisation of voice and noise may not have the same ‘energy’ contents and because the playback level (SPL) on the headphone is not a simple matter to adjust to an absolute value. Probably the best way would be to actually measure the SPL from the headphone using a dummyhead or an ear coupler. As In the Auralisation chapter in the Manual “Adjusting levels there is an alternative suggestion.”

A: The input you can use for simulating sound transmission in Odeon is the sound reduction Index for a certain type of wall.

Odeon does not take into account flanking transmission.

You can use Odeon for simulating sound pressure level in the receiving room from a well defined source, if the flanking transmission does not play the most important role in your construction, compared to e.g. the room acoustic complexity of the rooms. If you know the influence of the flanking transmission you can manually include it in the sound reduction Index for the wall.

It is important to check the reflection density in the receiver room. (You do that from a point response / reflection density). It should be more than 50 if you want good results. If it is less you should increase the number of rays.

To make simulations according to measurement standard, remember to use the required amount of sources and receivers.

A: The Quick Estimate should be used in connection with a rough distribution of materials. The Global Estimate is good for regular rooms, to estimate the reverberation time for selected source positions to give a fast and reliable average over the entire volume. If the model has coupled rooms or the reverberation time is very important for certain positions Point/Multi point response should be used. If the room is an auditorium with an audience, the grid response receivers should be used; e.g. with the statistics from the grid response.

A: This is probably due to low diffusion of surfaces in the room, and 1-dimentional reflection paths. The decay curve will not be linear but will have a steeper curve in the beginning and a less steep curve for the later reflections. With nonlinearity in the decay curve a larger number of reflections is necessary to simulate the reverberation time. also coupled rooms with non linear decay curves should have a large number of rays in the room setup. These are good examples of a volume, where a simple Sabine calculation will not be enough to calculate reverberation time.

It can be a help in cases with nonlinear decays to look at the Global Estimate, to analyze how many rays are necessary to define the decay curve (The Global Estimate should a least go down to – 35 dB at all frequencies).

A: The reverberation Time T₃₀ and EDT was selected from the beginning as these two reverberation times is enough to know the room acoustics. However, T₂₀ and T₃₀ are both calculated in the Global Estimate.

Reverberation time, (T₃₀) is derived from -5 to -35 dB of the backwards Integrated energy curve according to FDIS 3382-1[6]

See below how you can analyze the decay curves from a point response in the Auditorium or Combined edition. The point response shows all curves in the 8 octave bands, to investigate decays curves in a single octave band further press A. By zooming in on the backwards integrated energy curve (E, Integrated) you can analyze different steps of the decay e.g. to see how calculations of reverberation time based on different intervals of the decay curve give different results.

A: Check 3DopenGL and ray tracing if the point-, line- or surface- sources are inside the room and transmitting most of the sound energy into the room. Make also a 3DopenGL check of the receivers. If using a grid map it is possible to exclude receivers outside of the room from being displayed in 3DGrid when the chosen parameter is over or under a selected range. This is set in the Options/Program setup/Grid colours.

A: There are several examples of comparisons; both Round Robins, and other cases from different projects. comparisons of both SPL, RT and STI are available.

A: Odeon and other Room acoustics software are energy based high frequency models. Calculations are in 1/1 octave bands because it gives better results for energy based calculations.

In cases with wall transmission it is possible to use 1/3 octaves as input, but then Odeon will recalculate these to 1/1-octave bands in order to fit with the best calculation principle for this type of model.

A: The calculation principles applied in Odeon is a combination of high frequecy models such as the image source method and ray-tracing, therefore validity of results depends on the frequency range of interest and if signals of interest are dominated by pure tones.

For Odeon simulations as with real measurements, the source and receiver should be at least 1/4th wave length from the walls. But at the very lowest resonance of the room the level can change a lot from position to position without Odeon being able to predict it. For investigation of low frequency behavior (resonances), indeed Odeon is not the tool.

Although small (Non diffuse) rooms is a challenge to Odeon, it might in some cases be the best tool for your calculations anyway. This report suggest that absorption should be chosen with care if predictions in rooms with very none diffuse sound fields are made, in particular be careful with extreme absorption coefficients (alfa > 0.9 and alfa < 0.05).

A: The reflectogram and the reverberation curve is shown as sound pressure level(dB) as the BRIR is given in pressure (P). P is a more sensitive measure than dB (10*Log10(p^2)), and therefore the BRIR shows small details more clearly. Also BRIR has all frequencies included in the response at the same time. And especially the low frequency contribution that are almost not audible can have a strong visual influence on the BRIR.

Due to the sensitivity of the BRIR also the differences between right and left ear can seems very strong compared to what one would expect from two measurements so close together.

Even when source, receiver and room are all ideal symmetrical there will always be a small difference between right and left ear due to the calculation method for sound distribution used in Odeon.

Finally the HRTF´s used in the BRIR calculations will be shaped to contain some asymmetries.

A: Select the unity HRTF in the auralisation setup – delete the text contents in the Headphone input box (turns read which is ok in this case) finally set the phase approximation to random. This will produce a BRIR where both channels are equal.

A: Try to bring the work files down to your computer for comparison. The speed of the calculation can have something to do with the speed of the network. Also if you make very heavy calculations it might take some of the network capacity from others.

A: In order to speed up point response calculations, try making a calculation at one of the most critical positions, e.g. where coupled room effects are present. (Auditorium and Combined editions only)

Before calculating the point response, set the calculation parameters in the Room Setup. Use the standard Engineering setup as a basis. Set the Impulse Response Length to a value between 2/3 and 1 times the expected Reverberation time. Set the Impulse Response Resolution to a value around 1/1000 – 1/500 of the Impulse Response Length.

Calculate the point response in the selected critical position.

Check the following in the Single Point Response (Auditorium and Combined editions only)

1. Is the T₃₀ calculated at all frequencies? If not, a result of 0 s appears at some frequencies. This indicates that the Impulse Response Length is not long enough; change this in the Room Setup.
2. Compare EDT and T₃₀. In simple, well-behaved rooms they should not differ very much; typically EDT is a little shorter than T₃₀. However, in the case of coupled volumes and no direct sight from the receiver to the source, EDT can be longer than T₃₀.
3. Look at the decay curves; are they reasonably smooth? Look also at the squared impulse responses (Press A to switch from the display of integrated decays at all frequencies); the fluctuations should not have very strong spikes.
4. Look at the Reflection Density; values between 30 and 100 / ms should normally be sufficient. If it is less than approximately 30 / ms the number of rays should be increased for reliable results.

If the quality of the results above is not satisfactory, the Room Setup should be changed as follows

1. Increase the number of rays, (e.g. a factor of two should lead to the double reflection density).
2. Increase the Desired late reflection density; in some cases the actually achieved density in the point response calculation may be significantly less than the desired value in the room setup.

If the quality of the results above is satisfactory, but you want to minimize the calculation time, try decreasing the number of rays and shortening the Impulse response length.

If you are in doubt whether the results are good enough or not, try to run a point response calculation using the Precision setup. In most cases this will create a very high reflection density, but in rare cases like an open air theatre the number of rays may need to be set even higher. Use the calculation results as a reference, i.e. the results obtained with the optimized setup should not deviate significantly from these results.

Grid Response calculations
For initial calculations consider using a grid with large distances between receivers or instead use Multi point responses with discrete receivers at strategic positions. Only for the final calculations make a detailed grid calculation.

A: You may run two instances of ODEON with different rooms - at full speed with a DUAL-CPU, so it is indeed possible to benefit from multiple CPU's with ODEON. A single instance of ODEON will though not benefit from multiple CPU's.

It is not likely that we will implement support for multi-processor calculations in ODEON. This will, as a paradox, be extremely complicated because of the speed optimizations already made - indeed some core calculations can not be parallelised - such as the image tree method above (3).

The consequence of the optimizations mentioned above are that Odeon is typically 10-100 times (!) faster that than competing products for results of comparable quality (for geometries with some 500-1000 surfaces - for more complicated rooms the benefit is even higher).

A: Yes as well as scattering dependent of size of surface and distance between surface and source/receiver. read more in the following paper proceeding:

A: Yes much effort has been put into optimizing the calculation speed of ODEON over the years. It is not possible to mention all techniques implemented - here is just a few examples.

Odeon uses a dynamic sized 3D-cubenet in which it is stored, which surfaces intersect which cube in the cube-net, therefore Odeon only has to analyse a few of the surfaces in a room for each wall /ray collision instead of all surfaces.

From version 8.5 and up, ODEON make use of CPU specific instructions (MMX, SSE, SEE2…) in order carry out multiple calculations in one operation (e.g. multiplying x, y and z of a coordinate with a constant in just one operation instead of three). So indeed parallel processing is performed. Image sources are detected by use of ray-tracing. Rays will only detect image sources which are likely to be valid whereas the traditional image source method requires an enormous amount of image sources to be calculated of which only a few will be valid. Odeon keeps track that a given image source reflection is only added once to the impulse response by use of a tree data structure (image source tree). Therefore there are no cases where an image source is included twice in an impulse response as is the case for the Cone tracing method.

Apart from the above, the ‘Late-ray’ method is capable of producing many reflections at a receiver with just a few rays. For a description of the calculation method please see the ODEON manual.

A: Look under Dongle Update, or contact us.

A: No model is water tight. Odeon has a lot of different input files to simulate the room as accurate as possible, but a lot of input also gives a lot of possibilities of making mistakes. So it is a good idea to check your model carefully, and if possible let your colleagues look at it also, to assure the best results.

You can see some comparisons between Odeon simulations and measurements on the demo page for 2^nd Round Robin and 3^rd Round Robin III.

If you are using version 8 or later, the results are outdated. One conclusion with Round Robin III was that you should use the simple geometry model - however that is not the case if using version 8 or later with the reflection based scattering coefficient.

In any case Odeon performs much better today, using the RFB method or not (see the two PTB examples which installs with Odeon - they include measured as well as simulated results as part of the Multi Point Response jobs, at the 'Measured versus simulated' tab.

See also the following ref. for details:

Xiangyang Zeng, Claus Lynge Christensen, Jens Holger Rindel. Practical methods to define scattering coefficients in a room acoustics computer model. Applied acoustics Vol. 67, 2006, p. 771 - 786.

A: Odeon file sets including directivity patterns and room models are forward compatible, so it is possible to load old room sets from version 3, 4, 5, 6, 7 and 8 into version 9. The file set of Odeon version 9.0 and newer is not backward compatible. If insisting on loading a room into an old version from a new one, it is better to use the "File|Open room and repair" rather than the normal "File|Open room". Also it is recommended to make a backup copy before reloading into the older version.

Compatibility between different Editions is not a core facility in Odeon, so a bit of care and effort is required if loading a room created in another Edition. If loading a room in another Edition than the original, make a backup copy in the original Edition and open the room with the "File|Open|Room and repair" option.

Industrial
Is not capable of handling "single point response" result- and auralisation- files along with a number of acoustical parameters.

Auditorium
Can´t handle line, surface or multi surface sources. Any such source should be erased before attempting to load a room created in Industrial or Combined into Auditorium. Rooms created in the Industrial Edition does not have information about "Receiver pointing towards Source" in the JobList, so this has to be specified before calculations can be made.

Combined
Can read sets from any edition of Odeon. Only the facilities available in the original edition will be available. To make all options available the "Open|Room and repair" option should be used. Rooms created in the Industrial Edition does not have information about " Receiver pointing towards Source" in the JobList, so this has to be specified before calculations can be made.

A: This is described on the product pages along with the difference between different Editions: Industrial, Auditorium and Combined.

A: The 32 bit IEEE float is a professional format. When using this format you avoid introducing quantization noise. When using a PCM format such as the 16 bit integer format, samples are rounded into 16 bit integer data. By rounding the sample data, a difference between the original data (floating point data) and the data saved in the PCM file may (or rather will) occur - it is the difference between these two signals which is the quantization noise. Quantization noise is exactly that: Noise! and as such it is undesired. Further this type of noise may sound quite nasty (include harmonics). When creating multi source auralisation, many auralisation files are mixed together and this will accumulate noise - including the quantization noise in PCM files. If mixing two files with an equal level of noise - then the level of noise is doubled (+3dB), if mixing 10 files then the noise level increases by 10 dB and if mixing 100 files then the noise level increases by 20 dB. By using the float format at least the quantization noise is avoided.

A: Windows XP does by default not have a codec installed for this format, however there is a free codec package 'DC-DSP' available on the web. When this was written it could be found at
http://www.codecsdownload.com/DC_DSP_Filter_download.htm and had the version number 1.03. When this package is installed, all wave file formats that can be generated by ODEON are supported for playback (except the 32 bit PCM format). If you have installed programs such as 'Adobe Audition', then codex for these formats should already be installed.

A: Odeon can produce loudspeaker mapped wave files in the WaveFormatExtensible format. This is fully compatible with Windows media player version /10/11 - thus you may use features in this application such as play lists - be aware the wave files can become quite large (3 times normal stereo waves for a 5.1 Surround Sound set files)

A: In Odeon you describe your desired loudspeaker configuration *(e.g. a 5.1 Surround Sound set) along with its speaker positions. If this setup do not fully mach the physical one, then windows will try its best to remap the signals to whatever speaker layout is available to Windows - best results are of cause achieved if the layout entered in Odeon matches the one in windows(defined in the soundcards speaker setup for a sound blaster card) as well as the actual speaker connected to the soundcard.

A: When you are in Define Grid and Set manually scale grid, be sure to tick the box Manual Scaling before you define the interval you want to show in the grid. Choose the parameter you want to change.

If you still cannot make the exact scale you want there are some possibilities to adjust the range and colours in Option/Program setup/ grid colours.

When you have found a good grid scale setup, you can save it in Set manually scaled grid pressing (Ctrl S).

A: Read More.

A: Read More.

A: There can be several reasons for this error message. Most likely the course for the error is that the drawing file contains BLOCK and ACIS (3DSOLID, REGION, BODY) entities. In AutoCAD you can check what kind of entities your model contains with the LIST command.

The most successful approach is to bypass the .dxf file format and rather use the .3ds format which can be imported by Odeon. To export in the .3ds format from AutoCAD, use the 3DSOUT command.
The 3DSOUT is by default not Available in AutoCAD 2007, however "The 3DS Utility is available here. To install and use the plug-in, do read this installation note.

The problem can also be solved in earlier versions of AutoCAD by selecting the relevant drawing entities from inside AutoCAD and applying the EXPLODE command:
- If you EXPLODE a 3DSOLID model without BLOCKS one time you will get a model in 3DFACES (a POLYLINE entity) which is fine for .dxf import in Odeon. Use the ASIC/Solid command in the Odeon import menu.
- If you EXPLODE a 3DSOLID twice it will convert it from 3DSOLID->POLYLINE (mesh)->LINE entities. The POLYLINE entity can be imported by Odeon however the LINE entity does not carry sufficient information.

If you have not modelled in 3D solids try to use the Full re-import command in the Odeon import menu this might give you something you can use as well.

A: When you have located the surfaces of the object you want to copy in the OdeonEditor, you copy these surfaces together with all the points to a new editor. Save and load the new room in Odeon. Now to get rid of all the extra points it might be necessary to export the model to DXF and then import it to Odeon Again. This is possible from the file menu.

When this is done you should use the MTranslate function to insert the object back into the room. And use the NumbOffset function to make sure the new copied objects do not interfere with the existing point and surface numbers.

• A: Correct for errors which may reside in a CAD model, such as warped or repeated surfaces or surfaces with no area
• Stitch surfaces together to form models that are easier to handle, looks much nicer, and are better compatible with the calculation principles applied in ODEON

The following technical note covers these issues:
 ODEON Import of CAD files in the DXF format – problems and solutions.

A: Odeon can do even better. We have created a plug-in SU2Odeon for Google Sketchup which converts and saves the geometry directly in Odeons native .par format (Odeon version 10), it is available for download here. The plug-in is without any additional charge and works with the free as well as the pro version of Google Sketchup.

For version 9 and earlier of Odeon this solution may work
Odeon can not read .skp files, however, it is not a problem to use Google Sketchup as room modelling software together with Odeon. The solution is simply to export the model in either .dxf or .3ds format. Odeon is able to directly import these files as exported by Google Sketchup Pro - no need for extra software packages.

A: Yes below video describes how you can combine two extrusions from two different extrusion planes: a plane section and a cross section. Note that when you have combined the two models you cannot go back to the extrusion modeller and draw in the combined model, you must use the Odeon Editor.

A: Odeon A/S will probably not incorporate Industrial Foundation Classes (e.g. .ifc or .ifcxml files) in Odeon in the nearest future. However from programs such as AutoDesk Revit it should be possible to export geometries in the DXF format for use in Odeon. If the IFC support is merely export in the IFC file format without a tight integration of data then there is only little advantage of exporting in IFC compared to DXF.

A major problem with the IFC concept is that it assumes that we are linking the calculations up on the same model, whereas we with a model such as Odeon’s tend to alter the geometry during import in order to make the model compatible with the calculation model in Odeon (avoiding small surfaces and having watertight models etc).

Another obstacle is that it is not enough to implement the support in Odeon

- an implementation of the Odeon relevant data should also be available in the other programs (if the architect etc. should be able to define/alter material etc. in the database using their CAD program(s)). And because the data needed by Odeon/CATT/EASE etc. differs because their calculation principles are different there can't be made an implementation common to all such programs. The room acoustics extension to IFC for one program, in this case Odeon, may even alter as the program develops, thus needs other data.

A: There are basically three ways to create a room model: import from dxf-files, extrusion modelling or parametric modelling in a text editor. Read More.

A: The problem could be that the lines cross ower creating a butterfly surface, like the surface shown below (100 101 102 103)

A: Precise surface equations for each surface in a room model are essential for all computations in a program such as Odeon. The surface equation Ax + By + Cz + D = 0 of a surface plane is based on an insertion point as well as a surface normal.

If all corners of each surface would be exactly in one plane and there were no limits to numerical precision of computers, there would not be a problem. Neither is the case, so in Odeon these equations are fitted from all points on the perimeter of the surface weighting their contribution relative to the area of the surface which the two closest edges describe – that is, very close neighboring points has little weight whereas distant neighboring points carry height weight. Consequently Odeon can handle surfaces with perimeter points that derivates quite a bit from the perfect plane. In early versions of Odeon such error would often lead a substantial loss of rays or plane equations which described the geometry poorly – the geometry had to be corrected over and over again.

Note that Odeon doesn’t mind which order the perimeter points of a surface is given (clockwise or counterclockwise) both sides of the surface is automatically described in one go.

Also note that Odeon allows concave surfaces, surfaces with shapes such as U,O,L,H are allowed to be described by just one surface (sequence of points), no need for surface subdivision.

Although these are features are hidden, it does mean that modeling is made much easier by Odeon.

A: Yes the room volume calculation is available from the Quick Estimate in the Material List and from the Global Estimate. The volume estimate in quick estimate is slightly more precise. Use the F1-key in Quick Estimate to learn about the volume estimation method and its limitations. The surface areas are displayed directly in the Material List.

A: If the directivity data of interest is not available in the CLF format, then assist the CLF-group by encouraging the manufacturer to make such data available. Free tools for this purpose can be obtained at www.clfgroup.org.

A: In version 9 and later it is possible to use subdirectories for directivity files. This makes it possible to organize directivity patterns in folders e.g. to keep directivities from a specific manufacturer in a folder of its own making it simpler to make use of large libraries of loudspeakers. Simply make subdirectories for each loudspeaker manufacturer in the above mentioned directivity files directory and store the relevant directivity files there.

A: If you are not particularly interested in the result in receiver positions on the other side of the "walls", we cannot recommend to use the sound transmission modelling. Particularly with low sound insulation (R < 10 dB) the method has some drawbacks, please see paper from BNAM 2008.

You can either use absorption only, or a combination of transparancy (same for all frequencies) and absorption; this will work as shown on the last page of this old Powerpoint presentation.

A: If you do text export from the Decay Curve in the Single point response (Ctrl A), Odeon will not only export the normal energy-time histogram (with the resolution given in the ‘Room Setup’, also the intensity given by X,Y,Z composants are given: This text-export include early (specular as well as scattered) and late energy. It is not the individual reflections rather a sampling with a selected time resolution.