Thursday, March 22, 2018



OTL-Acoustics Lib: The Rosetta Stone of Acoustics Library and PEMARD-Framework, Features

Acoustics Calculations

OTL-Acoustics Lib and PEMARD-Framework can perform acoustic calculations on 3D environments, for indoor and outdoor environments. OTL-Acoustics Lib and PEMARD-Framework can calculate the following phenomena

  • 3D representation of acoustical space (sources, receivers, walls, barriers, grounds)
  • Distance Attenuation
  • Atmospheric Absorption
  • Finite impedance boundaries and objects * 
  • Reflection, using spherical wave reflection coefficients* 
  • Reflection calculation using plane wave absorption coefficient
  • Diffraction
  • Fresnel Zone correction for finite objects reflections (and soon for finite edge diffractions)
  • Atmospheric Turbulence
  • Frequency domain calculations
  • Time domain calculations
  • Calculation of Transfer Functions and Impulse Responses and parameters such as SPL, Excess Attenuation, Insertion Loss, RT, EDT, STI, and many more. 
  • Frequency analysis 
  • Coherent summation of sound path contributions*
  • Coherent and incoherent source summation
  • ISO 9613-2 “Attenuation of sound during propagation outdoors -- Part 2: General method of calculation” and soon to be adopted equivalent ANSI S12.62-201X

Path Detection

OTL-Acoustics Lib can also perform independent path detection on predefined 3D environments. The paths can be used for further acoustical calculations or for further processing. OTL-Acoustics Lib can

  • Detect reflections to any order using an efficient visibility tracing algorithm
  • Detect diffractions between edges to any order using a combination of BFGS and other numerical techniques
  • Detect reflected/diffracted and diffracted/reflected paths for certain objects within the geometry
  • In-depth sound path analysis (please see demo)

Extensibility and Flexibility

OTL-Acoustics Lib and PEMARD Framework are also extensible and flexible. Someone can use the whole power of the library and calculate acoustics phenomena for 3D environment but also use only parts of the engine library for his needs. For example, someone might want to use only the path detection engine of the library and then apply his own calculation methods for the various phenomena. The opposite is also possible. Someone can add predefined sound paths in the engine and perform acoustical calculations on them. OTL-Acoustics Lib and PEMARD-Framework have the following extensibility and flexibility features

  • Ability to choose between various acoustic phenomena to be calculated
  • Ability to introduce new calculations
  • Ability to calculate predefined paths
  • Ability set criteria for path detection like reflection and diffraction order, path length and path importance.

Future Features

OTL-Acoustics Lib in time will be enhanced with the following features:

  • Wall roughness scattering
  • Finite Edge Diffraction
  • Atmospheric Refraction

* The use of spherical wave reflection coefficient (versus plane wave) has been proven to provide more accurate predictions both for indoor and outdoor sound propagation. Please see for example, the paper "Prediction of reverberation time and speech transmission index in long enclosures" by Kai Ming Li et al, (J.Acoust. Soc. Am. 117 (6), June 2005) where the combination of spherical wave reflection coefficient with impedance boundaries and coherent summation of sound path contributions yield accurate prediction of reverberation time, early decay time, and sound transmission index.