Solutions and tips regarding various simulation topics.
Q: Can I make simulations in a room when there is loss of rays?
A: ODEON will complain when the loss of rays is more than 20% and the calculations will be terminated. Ideally a room should be watertight. Otherwise the software cannot know the path that each ray follows. If a ray escapes from the room there is not any reflection point or any information for its successive course. When there is loss but it is lower than 20% ODEON accepts the geometry since the missing energy is not so much to deteriorate the accuracy.
Q: Can I calculate structure borne sound transmission or flanking transmission in ODEON?
A: No. ODEON treats sound transmission - insulation in a simplified way. Only airborne transmission is modeled, as rays which are let to pass through a partition. No matter how high is the reduction index, only 10% of the total number of rays are let to pass through the wall. The strength of these rays is then reduced according to the reduction index. It wise to use slightly higher number of rays when modelling sound transmission, so that you are sure that enough rays will pass from a source to a receiving room and sample the geometry properly.
If you want to make more advanced sound insulation simulations, such as impact or flanking transmission, you may have to check a more appropriate software like Bastian from DataKustik.
Q: Does Odeon have 1/3 octaves?
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.
Q: Can I use Odeon for small rooms: music studies, cars etc?
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).
Q: How do I get to look at the room impulse response for a single point receiver instead of the BRIR?
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.
Q: Odeon is installed on my hard drive but calculations are running on a network drive, can this influence calculation speed?
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. It is also quite common that the whole process may get stuck due to overload of the network
Q: Does ODEON support multiple CPU's
A: Since ODEON 11, which was released in 2011, multi core CPU's are supported for Multi point and Grid response calculations. The calculation engine has been rewritten to support this and even runs faster on a single core CPU. A history of the developments in ODEON can be found here.
Q: Are there any examples of comparison of Odeon simulations and measurements?