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Is Olive Tree Lab slow? Well, you can make it faster!

8/9/2015

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We have received a lot of questions and concerns recently by clients about Olive Tree Lab taking a lot of time to calculate results. Indeed, acoustics calculations in Olive Tree Lab usually take more time than on any other typical noise mapping or room acoustics tool. So, is Olive Tree Lab a slow software application? Well, it is an imperative that it always takes time to do things properly! Quality is not achieved with shortcomings. But does that mean that Olive Tree Lab users are doomed to eternal waiting? No, they are not! Of course, they will need to master their tool. Wild horses need great stallions and great tools need great users. It does not make sense for a Ferrari to be driven by my grandma.

In this post I will elaborate on some best practices on how to make calculations in Olive Tree Lab more efficient and spend less time in waiting. Before i get into these practices, i would like to mention that we do our best from our side to make the calculations as fast as possible without compromising on accuracy and without introducing physically unfounded methods. We use smart detection algorithms that use techniques like visibility tracing, prioritized tracing and hybrid tracing to accelerate image source detection and diffraction path detection. We are actively engaged in research in the area of accelerating path detection algorithms with relevant publications. We use parallel programming wherever this is possible and we have also developed GPU based acoustic calculations, waiting to be introduced as soon as we feel that the technology is mature enough for mainstream use.

Now let's see how we can make our calculations in Olive Tree Lab faster. First of all, in order to speed up the calculation process, we need to understand why it is taking so long. The most important bottleneck in the calculation process is the path detection process. All exhaustive path detection algorithms are of exponential complexity, where the exponent is the order of reflection or diffraction that needs to be detected. This means that the calculation steps increase exponentially as we increase the orders in each case. The number that is raised to this exponent is the number of surfaces or edges respectively. So the basic quantities we need to deal with in this case is the number of surfaces and the order of reflections and diffractions. The less are both quantities the much faster the calculations will be.

Other factors that affect the calculation time, not in an exponential way though but in a linear way, are the following a) Source-Receiver combinations. Calculations need to be executed for each source-receiver combination. So a model with 10 sources and 10 receivers will take 100 times more time to be calculated than a model with a source and a receiver. b) Sound Paths to be calculated. The less paths you need to calculate the faster the calculation will finish. c) Spectrum Analysis. The number of frequencies to be calculated affects linearly the sound path calculation stage.

Now that we have gone through the major parameters that affect calculation time, let's see how we can optimize it.
An important engineering principle in Olive Tree Lab calculations is that as we increase the calculation complexity, the results do not approach the solution in the same rate that the complexity increases. In computational terms the relation of accuracy increase to calculation complexity increase is a sublinear function. As a result, an OTL user should find the fine balance between accuracy and calculation time. In other words he/she should make the calculations as complicated as the expected accuracy justifies them to be.

So how do we achieve the above? Let me outline my approach on this in a typical large project. Let's suppose a project with 500 surfaces, 10 sound sources and sound receivers. I would do the following.
1) Make all the obviously irrelevant surfaces in the model inactive (walls that will obviously not contribute to the sound field).
2)Choose a representative Source-Receiver combination and deactivate the rest.
3)Run a simple calculation with a very basic complexity e.g. first order reflections, first order diffractions and 1/3 octave calculations. 
4)Progressively increase the calculation complexity and recalculate.
5)Compare subsequent calculation times and calculation results. Evaluate if the increase in accuracy justifies the extra cost in calculation time. Let's suppose that a calculation which took 2 minutes yields an SPL 0.5db higher than a calculation that took 10 seconds. In this case I might decide that it is not worth the additional time. While thinking about the time that I consider valuable, I can make some projections about the final calculation time e.g. with 2 minutes for a source receiver combination, we can estimate 200 minutes for 100 combinations compared to 10 seconds x 100, which is around 14 minutes.

6)As soon as I decide where i want to compromise between accuracy and calculation time, I enable all my sources and receivers and I execute my full calculation. 

The above procedure can be changed slightly based on the project requirements but it generally highlights what the way of thinking should be about getting optimal calculation times in Olive Tree Lab.

In the future, I will post more ideas on how to make OTL sound propagation calculations more efficient.
​
Stay tuned!
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Paragon Acoustic Consultants had been reviewing different room acoustics software packages to standardise the software used within the practice. Various room acoustic packages were considered, however, a number of the software packages considered proved unfavourable due to limitations of room geometries that can be modelled, limited calculation outputs and general concerns that the software was unnecessarily difficult to use for even straightforward tasks. This practice has reviewed Olive Tree Lab Suite and found the software to be user friendly whilst providing a very high level of functionality. Having rented the software and modelled a number of relatively complex room acoustic projects, we are impressed with the software and in particular the very professional back-up and support provided by P.E. Mediterranean Acoustics R&D. At this stage the modelling functions for outdoor sound have not been used, however, having watched demonstrations by Mediterranean Acoustics via computer link–up the external modelling sections of the software look as impressive as the room acoustics modelling.

John Gillott

Acoustics Consultant
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Paragon Acoustics Consultants, UK

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The OTL Team is a delight to work with. Amazingly responsive to questions and requests, and constantly improving the product. When it comes to software development & support, many should look at this company as a model to follow.

Dominique J. Chéenne

Ph.D.
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 INCE, USA

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I would like to appreciate the team of OTL and Premard in terms of their continued support and efforts. OTL has been such a valuable tool that I keep coming back for more. With the new software OTL 4 Pemard has again made an effective tool for Acousticians worldwide.

Abraham Berin

B. Tech E&MT, M.Sc A&A (UK)
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Head of Acoustics, INFOSIGHT, UAE

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​I have been using the OTL Lab application for a number of years, mainly for teaching and demonstrations at undergraduate and postgraduate courses in acoustics and noise control. The program is user-friendly and incorporates an advanced high-level 3D designer tool for setting up virtual acoustic environments, allowing easy setting up of case studies and extracting results and maps for radiation and transmission for noise and other sources.
I find very useful the advanced physics engine for sound propagation which allows for wave-based simulations (plane or spherical) considering also atmospheric refraction. This enables OTL to achieve accurate results especially in large scale setups encountered in environmental studies. The interface for immediate comparison of analytical results with standardized approximations (ISO standards) or simplified computational methods such as ray tracing and image-source models allows for comprehensive evaluations in multiple levels of physical detail. Such features which have been utilized by the members of our Audio and Acoustic Technology group during research projects.
The support by the OTL team was extremely helpful and their response immediate, tackling queries at personal level and providing educational webinars for the students.

John Mourjopoulos

Professor
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University of Patras

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OTL is an appropriate tool for prediction of acoustic adjustments in room acoustics, outdoor environment and industry. It offers flexibility and an ease of the ability to customize. Thanks for the multi-layered structure for impedance, absorption and SRI prediction.

Toufic Attieh

Technical Manager
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Gresam Acoustic & Vibration Engineering, Lebanon

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Although designed for demanding Acoustics applications, Olive Tree Lab has been instrumental in my research and work. Despite its hugely detailed modeling of acoustic properties, primarily addressed to acousticians, through its intuitive interface, it has also proven invaluable for architectural design. Furthermore, the Mediterranean Acoustics team have vastly exceeded my expectations for 'after sales service' and provided a rare blend of scientific expertise and personal care – giving true meaning to the word 'support'.

Ilias Papageorgiou

Architect
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Greece

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We find OTL very intuitive and the customer service spectacular. Once the model was properly configured, the mapping software predicted very accurately and was within +/-5dB in comparison to actual field measurements.  We were able to provide client documents that were clear and intuitive and allowed them to prove compliance with local and state noise ordinances.

Thomas N. Ryan

Senior Consultant
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Technological Design Studios, LLC.

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Pemard did a fantastic job with our custom software application. Costas and Panagiotis were extremely responsive during the development process and were always helpful in immediately addressing our concerns and fixing issues where we found them. The custom software the team developed for us has been of huge help to our room acoustics design process and we could not have done this without their help. I would recommend Pemard to anyone needing custom acoustics software.

Anonymous

Acoustics Consultants
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USA

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  • Home
  • About
    • Philosophy
    • Events & Training >
      • Past Events
  • Publications
    • Papers & Presentations
    • Research and Validation Projects
  • Acoustics Software & Tools
    • Olive Tree Lab Suite
    • Olive Tree Lab - Room Modes
    • Olive Tree Lab Acoustics Lib
    • SONarchitect
    • AFMG - EASE, SoundFlow, Reflex, Address, Focus, SysTune >
      • EASE - Enhanced Acoustic Simulator for Engineers
      • EASE - SpeakerLab
      • EASE - EVAC Fast Design of Acoustic Evacuation SystemsFast Design of Acoustic Evacuation Systems
      • AFMG SoundFlow - For the acoustic design of multi-layer structures
      • AFMG Reflex - For the design and application of diffusers
      • EASE Address
      • EASE Focus - Universal Sound System Modeling in 3D
      • FIRmaker - Put Your sound Where It Belongs!
      • EASRA - Electronic and Acoustic System Evaluation and Response Analysis
      • SysTune - Professional Audio Measurement
  • What's New
  • Services
  • Downloads
  • Purchase
  • Contact
    • Support