“Project” window¶

Presentation¶

Principle¶

The “Project” window allows to organize the set of useful data on three tabs “Scene” tab, “Calculation” tab and “Results” tab. It follows a natural procedure, for a classical acoustical study, which consists in:

Giving all information (geometry, material, sound sources, receivers…),
Gtarting the calculation (using a specific code),
Representing the results.

In the definition and the realisation of a calculation, users should follow the natural procedure:

Define all information/data in the tab “Scene” tab
Choose and parametrize the calculation code in the tab “Calculation” tab
Explore, process and represent all results in the tab “Results” tab

Definitions¶

All data, in each tab, are organized in trees, each tree containing folders (eventually with subfolders), each folder with elements. Each element is defined by several parameters that are showed in the ‘Properties’ window. These elements can be data, check boxes, character chains, scrolling lists, trees…

Avertissement

Data defined in the ‘Scene’ tree depend on the numerical code that will be used in the tab ‘Calculation’ (i.e. depending on the calculation code, it is not necessary to defined all elements. See the user guide/manual of the code for more information).

Note

Using Python scripts, users can add folders and elements in trees. This can be useful for integrating new numerical codes or specific processes. See the scripting guide of I-Simpa for more information.

Common features¶

Collapse/Expand a tree¶

A tree/branch can be collapsed (or expanded) by a:

click on the - (or the +) symbol in front of a folder in a tree;
double-click on the folder.

Copy/Paste function in a tree¶

The copy/paste function is valid in many folders and elements of trees. This can used to duplicate elements and folders in tree, or to copy elements and folders in a text editor (the format of elements is ‘XML’). Used the right click of the pointer (‘Copy’ and ‘Paste’ actions) to copy/paste elements.

Copy/Paste function in a spreadsheet¶

All data concerning an element are descried in a spreadsheet in the ‘Properties’ window. All cells of the spreadsheet (for a given element) can be copy/paste to another spreadsheet for an equivalent element. Copy/Paste is also functional to export data to an external spreadsheet software.

Rename an element in a tree¶

Excepted for predefined folders and elements, all new folders and elements created by users can be renamed, either when creating the element/folder, either after creation using the ‘Rename’ option (right click of the pointer on the element/folder to be renamed).

Remove an element from a tree¶

Excepted for predefined folders and elements, all new folders and elements created by users can be removed, using the “Delete” action (right click of the pointer on the element/folder to be renamed).

Create charts from tabular data¶

Creating charts¶

Most values represented as tables in a “Properties” window can be displayed in a chart form, configurable by the user. The procedure consists of selecting cells in a table of data, then, to click with the right mouse button on the corresponding selection and to specify options representation:

“Tab name”: Name of the tab containing the created a chart.
“Name of X axis”: Name of the x-axis.
“Name of X axis”: Name of the y-axis.
“Data alignment”: Choose the orientation of
“Text label for X”: Display labels of the x-axis in a “text mode” using a linear space, or in “value mode” using the real x value.
“Default Style”: Curves representation.

Note

The choice of colors (for curves, fills, dots…) in the representation of graphics is random.

Note

The labels of the data series (in tables) are automatically considered in charts.

Chart Options¶

Once the chart is created, several actions are possible, using the contextual menu on the chart.

“Original Zoom”

Reset to the initla display. Use the mouse (button left) to zoom in/out.

“Export”

“Export to image file”: export the chart as an image file (PNG, JPG, BMP).
“Export to clipboard”: user can paste the chart in antoher application.

“Show/Hide curves”

Select the curves to be displayed or “Show”/”Hide” all curves.

“Display parameters”

Configure all the chart properties.

“Scene” tab¶

In the “Data” tree of the “Project” window, user defines all needed information, in a acoustic point of view, in order to realize an acoustical calculation. This means, surface material, sound sources, receivers (punctual and plane), as well as other needed data in function of the numerical code (for example, the SPPS code can also take into account fitting zones).

In the “Project” tree of the “Project” window, user defines all general information (environmental data, configuration, information…) and common database (material and spectrum).

Avertissement

All data defined in the “Scene” tree depend on the numerical code that will be used in the tab “Calculation” (i.e. depending on the calculation code, it is not necessary to define all elements. See the user guide/manual of the corresponding code for more information).

Astuce

For data that depend on frequency, users need to define only the data for the frequency bands of interest, i.e. the frequency bands that will be used for the calculation.

“Data” tree¶

Fitting zone¶

The element “Fitting zone” allows to define one or more volumes of the geometry that contain scattering objects, producing acoustics diffusion. This phenomenon can have an important effect on the sound level distribution, as well as on other acoustical parameters (like reverberation time), in rooms such as in industrial halls, with many objects on the floor.

Most of time, the diffusion process is modelled using the concept of mean free path (noted Lambda or λ [m]) with a statistical approach defined by a diffusion law). On the same time, acoustical absorption (noted Alpha or α, between 0 and 1) can also occurred on the scattering object.

Within I-Simpa, the diffusion in a fitting zone, can be defined using two methods (Right click on the folder “Fitting zone” and Select the option in the contextual menu):

by creating a rectangular volume in the 3D scene (“Define rectangular fitted zone”) and by setting the diffusion parameters in the corresponding zone;

by detecting one or more volumes in the 3D scene (“Define scene fitted zone”) and by setting the diffusion parameters in the corresponding zones. This can also be done handly, by selecting all the face elements around a given volume and a point inside the volume.

Right click on the root “Fitting zone” folder to define a fitting zone:

“Define scene fitted zone”
Defines a fitted zone from the face elements of the 3D scene.

Avertissement

The volume must be a closed space.
- “Surfaces”
  Contains the scene surfaces that define the fitting zone.
  
  “Surface area”
  Total surface (in m²) of all face elements in the folder.
  
  The selection of faces can be made:
  
  by using the 3D view. See the section Surface selection for understanding how to select surface elements
  
  by drag & drop of all surfaces of a “Volume” element;
  
  by a direct conversion of a “Volume” element to a fitting zone (see section Volumes).
- “Properties”
  Defines the properties of the element.
  
  “Active fitting zone”
  (Un)check to (Des)activate the fitting zone.
  
  Note
  
  Depending of the parameters of the selected calculation code, all the fitting zones can also be desactivated at the calculation step.
  
  “Description”
  Gives a short text description of the element.
- “Inside position”
  Defines a point of coordinates (x,y,z) inside the volume. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
- “Display”
  Defines the parameters for displaying the element on the 3D view
  
  “Color”:
  Defines the color of the fitting zone.
  
  “Show name”:
  Check to display the name of the fitting zone on the 3D view.
- “Acoustics parameters”
  Defines the acoustics parameters of the fitting zone, by frequency band.
  
  “Alpha”
  Absorption coefficient of the scatterers.
  
  “Lambda”
  Mean free path (unit: m).
  
  “Diffusion law”
  Reflection law.
“Define rectangular fitted zone”
Defines a parallelepipedic fitted zone.
- “Acoustics parameters”
  Similar as for “Define scene fitted zone”.
- “Display”
  “Color”
  Defines color of the fitting zone in the 3D view.
  
  “Opacity”
  Defines opacity of the fitting zone in the 3D view.
  
  “Render mode”
  In the 3D view, the fitting zone can be represented by a zone with face (“Volume”) or a contour (“Borders”).
  
  “Show name”
  Check to display the name of the fitting zone on the 3D view.
- “Properties”
  Similar as for “Define scene fitted zone”.
- “Origin”
  Defines the (x,y,z) coordinates of the first point of the rectangular zone. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
- “Destination”
  Defines the (x,y,z) coordinates of the point opposite the “Origin” point of the rectangular zone. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.

Punctual receivers¶

Several acoustic indicators must be associated to punctual receivers in the volume of propagation. Besides their position and direction of view, it may also be necessary to define other acoustic properties, such as directivity, background noise… The receivers can be grouped within source groups. A group can contain other groups.

Right click on the root folder “Punctual receivers” to create new receivers or groups of receivers.

“New receiver”
Creates a new receiver.
“New Group”
Creates a new group of receivers.
“Create a receiver grid”
Creates a grid of receivers in a new group.
- “Number of receivers (column)”
  Number of receivers along a column.
- “Number of receivers (row)”
  Number of receivers along a row.
- “Column vector”
  Defines the (x,y,z) coordinates of the vector along the column.
- “Row vector”
  Defines the (x,y,z) coordinates of the vector along the row.
- “Grid origin”
  Defines the (x,y,z) coordinates of the grid origin.
“Rotation”
Rotate all receivers in a given group (See Manipulating sources and receivers for description).
- “Angle (degree)”
  Defines the rotation angle in degree.
- “Rotation center”
  Defines the (x,y,z) coordinates of the point of rotation.
- “Rotation vector”
  Defines the (x,y,z) coordinates of the vector of rotation.
“Translation”
Translate all receivers in a given group.
- “Translation vector” (See Manipulating sources and receivers for description)
  Defines the (x,y,z) coordinates of the vector of translation.
“Orientation”
Orient all receivers in a given group to a target point.
- “Target point”
  Defines the (x,y,z) coordinates of the target point.

Receiver parameters:

“Background noise”
Defines the existing background noise at the receiver location. This parameters can be useful, for example, to calculate some acoustics indicator for speech intelligibility. This parameter is defined by a background noise “Spectrum”. See the section Using spectrum for understanding how to use a spectrum in the application.
“Direction”
Defines the orientation of the receivers, using a vector of coordinates (x,y,z). This parameters can be useful, for example, to associate a directivity to the receiver. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view. The receiver can also be automatically oriented to a given sound source with a dynamic link: choose the corresonding sound source in the list.
“Display”
Defines the parameters for displaying the element on the 3D view.
“Color”:
Defines the color of the receiver.

“Show name”:
Check to display the name of the receiver on the 3D view.
“Position”
Defines the (x,y,z) coordinate of the receiver. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
“Properties”
Defines the properties of the element.
“Description”
Gives a short text description of the element.

“Direction x”
Coordinate x of the orientation vector (unit vector).

“Direction y”
Coordinate y of the orientation vector (unit vector).

“Direction z”
Coordinate z of the orientation vector (unit vector).

“Directivity”
Directivity of the receiver. See the Directivity section for details.

Sound sources¶

This element allows to define the acoustic properties of sound sources, such as the acoustic power, the directivity, the position of the source and its orientation. The sound sources can be grouped within source groups. A group can contain other groups.

Right click on the root folder “Sound source” to create new sound sources or groups of sound sources

“New source”
Creates a new source.
“New Group”
Creates a new group of receivers.
“Create a line of sound source”
Creates a line of sound source in a new group.
“All sources”
Possible actions on a group of sound sources.
“Enable”
Enable all sound surces in a group.

“Disable”
Disable all sound surces in a group.

“Rotation” (See Manipulating sources and receivers for description)
Same action as for sound sources.

“Translation” (See Manipulating sources and receivers for description)
Same action as for sound sources.

Sound source parameters:

“Display”
Defines the parameters for displaying the element on the 3D view.
“Position”
Defines the (x,y,z) coordinate of the sound source. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
“Properties”
Defines the properties of the element.
“Active source”
(Un)check to (Des)activate the sound source.

“Description”
Gives a short text description of the element.

“Direction x”
Coordinate x of the orientation vector (unit vector).

“Direction y”
Coordinate y of the orientation vector (unit vector).

“Direction z”
Coordinate z of the orientation vector (unit vector).

“Directivity”
Selects the directivity of the sound source in a list. Several “theoretical” directivities are proposed (omnidrectionnal, unidirectionnal, XY, YZ, ZY) as well as “balloon” directivities (i.e. as measured). In this last case, the “Balloon” parameter must be given.

“Directivity Balloon”
Selects the directivity balloon of the sound source in a list. This parameter is enable only if the “Balloon” option is selected in the “Directivity” parameter.

“Time delay”
Defines a delay (in second) for activating the sound source.
“Sound power”
Defines the sound power of the sound source. This parameter is defined by a power “Spectrum”. See the section Using spectrum for understanding how to use a spectrum in the application.

Surface receivers¶

It is common in a acoustics study to focus on the distribution of sound levels on a surface (noise mapping). The concept of mapping can also be generalized to the surface representation of any acoustic parameter, like reverberation time, clarity… The I-Simpa interface enables to define surfaces for the representation of maps.

By right clicking on the root “Surface receiver” folder, it allows define two types of surface receiver:

“New scene receiver”
Surface elements of the 3D scene can be selected.
- “Surfaces”
  Defines the surface element of the 3D scene to be considered for the surface receiver. See the section Surface selection for understanding how to select surface elements.
  
  “Surface area”
  Total surface (in m²) of all face elements in the folder.
- “Properties”
  Defines the properties of the element.
  
  “Description”
  Gives a short text description of the element.
“New plan receiver”
The surface receiver is defined by a grid cutting plane, made of 3 vertices A, B and C.
- “Display”
  Defines the parameters for displaying the element on the 3D view.
  
  “Grid color”
  Defines the color for displaying the grid.
  
  “Show grid”
  Check to display the grid on the 3D view.
  
  “Show vertice names”
  Check to display the name of the vertices A, B, C.
- “Properties”
  Defines the properties of the element.
  
  “Description”
  Gives a short text description of the element.
  
  “Enable”
  Check to enable the plan receiver in the calculation.
  
  “Grid resolution”
  Defines the resolution of the grid (in m).
- “Vertex A”
  Defines the (x,y,z) coordinates of the vertex A. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
- “Vertex B”
  Defines the (x,y,z) coordinates of the vertex B. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
- “Vertex C”
  Defines the (x,y,z) coordinates of the vertex C. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.

Surfaces¶

This element contains all surfaces of the scene. These surfaces are either created within I-Simpa in the case of a the creation of a parallelepipedic geometry or imported. In the last case, depending on the software used to create the 3D scene, it is possible to import faces that are already organized into groups. This group organisation allows to easily affect specific material (with specific acoustic properties) for each surface group.

Right click on the root folder “Surfaces” to organize the face elements:

“Add a group”
Creates a new group.

Right click on a group to perform actions:

“Inverse face normal”
Change the orientation of the normal of all face elements within the group. This can useful if, at the importation of 3D scene, some original faces have a wrong orientation.
“Properties”
Defines the properties of the element
- “Material”
  Select the material to affect to the surfaces group, from a list. The list is defined in the “Material database” of the “Project tree”.
- “Surface area”
  Total surface (in m²) of all face elements in the folder.

Volumes¶

The volume element allows to define volumes of interest in the 3D scene. You can “handly” create a volume from face elements in the 3D scene or automatically detect all existing volume in the 3D scene. This can useful to create or detect fitting zones.

Right click on the root folder “Volumes” to manage “Volumes”:

“Create a volume”
Creates a volume from the face elements of the 3D scene.
- “Display”
  Defines the parameters for displaying the element on the 3D view.
  
  “Domain color”
  Defines the color for displaying the volume.
- “Inside position”
  Defines a point of coordinates (x,y,z) inside the volume. The position can be defined by filling the form or using the pointer on the 3D view. See the section Defines position for understanding how to define a location with the 3D view.
- “Properties”
  Defines the properties of the element
  
  “Calculate the mean free path”
  Calculate the mean free path using the classical formulae from statistical room acoustics (λ=4V/S, with V the volume and S the surface of the volume).
  
  “Mean free path”
  Value (in m) of the calculated mean free path.
“Volume auto-detect”
Automatically detect all volumes within the 3D scene. Same paremeters as for “Create a volume”.

“Project” tree¶

Configuration¶

This element of the “Project” tree defines some useful information concerning the project. These element are not used for the calculation.

Property elements: these elements are all optional.

“Author”
Name or information concerning the author of the project.
“Date”
Date of the project. By default, it is the date of creation of the project (text).
“Project description”
Quick description of the project.
“Project name”
Name of the project, given by the author.

Display¶

This element of the “Project” tree defines some useful parameter for the 3D display.

Property elements:

“XYZ axis”
Define some parameters for the graphical representation of the geometric coordinates.
“Arrow color (x)”
Open a dialog box for selecting the color of the arrow of the x-axis.
“Arrow color (y)”
Open a dialog box for selecting the color of the arrow of the y-axis.
“Arrow color (z)”
Open a dialog box for selecting the color of the arrow of the z-axis.
“Arrow length”
Length (in m) of the arrow of the xyz-axis.
“Arrow widh”
Width (in m) of the arrow of the xyz-axis.
“Grid size”
Size (in m) of a grid element.
“Grid color”
Open a dialog box for selecting the color of the XYZ grid.
“XY Grid”
Enable/disbale the display of the XY grid.
“XZ Grid”
Enable/disbale the display of the XZ grid.
“YZ Grid”
Enable/disbale the display of the YZ grid.

Environment¶

This element of the “Project” tree defines some useful environment data.

Avertissement

The use of these information depend on the calculation code. See the reference guide of the numerical code for more details. The code can enable the calculation of the atmospheric absorption and of the meteorological effect (considerig a log_lin celerity gradient) with a ground description using the roughness parameters.

Property elements:

“Atmospheric absorption - User defined”
Enable/disable the selection of the value of the atmospheric absorption.
“Atmospheric absorption - Value”
User value of the atmospehic absorption. This option is available only if the option “Atmospheric absorption - User defined” is enable.
“Atmospheric pressure (Pa)”
Atmospheric pressure(Pa).
“Meteorolical effect - Celerity gradient a_log”
Value of the a_log paremeter of the log_lin profile celerity. The default value is function of the option given by the “Meteorolical effect - Profile”, but can be modified by the user.
“Meteorolical effect - Celerity gradient b_lin”
Value of the b_lin paremeter of the log_lin profile celerity. The default value is function of the option given by the “Meteorolical effect - Profile”, but can be modified by the user.
“Meteorolical effect - Profile”
Defines a log_lin gradient profile. By selecting one of the following options, it sets the “Meteorolical effect - Celerity gradient a_log” and “Meteorolical effect - Celerity gradient b_lin” parameters. However, these values can be modified by the user.
“Very favorable”
a_log=+1, b_lin=+0.12

“Favorable”
a_log=+0.4, b_lin=+0.04

“Homogenous”:
a_log=0, b_lin=0

“Unfavorable”:
a_log=-0.4, b_lin=-0.04

“Veryfavorable”:
a_log=-1, b_lin=-0.12
“Relative humidity (%)”
Relative humidity of air (%).
“Roughness - z0 (m)”
Value of the ground roughness (m).
“Roughness - Ground type (m)”
Defines the ground type. By selecting one of the following options, it sets the “Roughness - z0 (m)” parameter. However, this value can be modified by the user.
“Water”
z0=0.006

“Ground”
z0=0.02

“Short lawn”
z0=0.001

“Dense lawn”
z0=0.02

“Wheat (1m height)”
z0=0.16

“Sparse habitat (farm, trees, hedges)”
z0=0.6

“Low concentration Suburb (residential areas, gardens)”
z0=1.2

“Dense urban”
z0=10

“Dense suburb”
z0=1.8
“Temperature (°C)”
Temperature of air (°C).

Informations¶

This element of the “Project” tree gives some useful information concerning the I-Simpa project.

Property elements:

“Model face count”
Number of face elements.
“Number of active fitting zones”
Number of active fitting zones.
“Number of active sound sources”
Number of active sound sources.
“Number of fitting zones”
Number of fitting zones.
“Number of punctual receivers”
Number of punctual receivers.
“Number of sound sources”
Number of sound sources.
“Number of surface groups”
Number of surface groups.
“Scene surface (m2)”
Scene surface (m²).
“Scene volume (m3)”
Scene volume (m3).

Note

The scene volume is displayed only after a first meshing of the scene. Generate a meshing using the Meshing Toolbar (see Meshing option)

Project database¶

See a detail descritpion of the Project database

“Calculation” tab¶

This tab allows to choose and to define the acoustic calculation. This tab contains all calculation codes that are linked to I-Simpa. By default, two numerical codes are given:

TCR calculation code
Apply the Classical Theory of Reverberation for room acoustics. It applies Sabine and Eyring formulae. This code must be used only for closed spaces
SPPS calculation code
This code is based on a particle tracing method, in respect with the geometrical and energetical hypothesis. This code can be applied in most of situations in room acoustics, as well as in open field, including urban area.

Important

Read the corresponding documentation before using these codes.

Using SPPS within I-Simpa¶

SPPS is already embedded in I-Simpa. Follow the next instructions to run a calculation with the SPPS code in I-Simpa.

Double left click on the TCR calculation code in I-Simpa to display all calculation paramaters:

Frequency bands for the selection of the frequency band to be used for the calculation
Meshing for the meshing configuration
SPPS Calculation parameters for the calculation parameters

Right click on the selected calculation code to display all possible actions:

Run calculation
Job list

Frequency bands¶

This allows to define the frequency band that will be used for the calculation. This can be done:

by hand, by checking/unchecking the frequency to be considered;
automatically (“Automatic selection”), by using the contextual menu on the element “Frequency band” of the chossen code:
- “Unselect all”
  Uncheck all frequency bands.
- “Select all”
  Check all frequency bands.
- “Octave”
  Check third ocave bands that are centred on the corresponding octave bands.
  
  “All”
  All octave bands on the whole frequency range
  
  “Building/Road”
  All octave bands between 125Hz and 4000Hz.
- “Third octaves”
  Check the third octave bands, considering.
  
  “All”
  All thrid octave bands on the whole frequency range.
  
  “Building/Road”
  All octave bands between 100Hz and 5000Hz.

Meshing¶

Some calculation codes may require a meshing of the domain (SPPS for example). I-Simpa used the TetGen meshing code (A Quality Tetrahedral Mesh Generator and a 3D Delaunay Triangulator). See the documentation for more information.

Within I-Simpa, TetGen can be paramatrized:

“Test mesh topology”
Check/uncheck for activate the debug mode of TetGen (debug mode).

Avertissement

With the debug mode, the meshing is not realized.
“Additional parameters”
Add parameters to the TetGen default parameters.
“Radius/Edge ratio”
Defines the ratio between the radius of the sphere that would contain a mesh and the lenght of the mesh. This parameter could be useful in order to avoid long meshes.
“Scene correction before meshing”
Check/uncheck for trying to repair the 3D scene if possible.
“User-defined paramters”
Defines new parameters by replacing default parameters.
“Surface receiver constraint”.
Check/uncheck for using a given value of the mesh surface “Surface receiver constraint (m²)”.
“Surface receiver constraint (m²)”
Maximun accepted value of the mesh surface (m²) for a surface receiver. The value can be modified only if the “Surface receiver constraint” parameter is checked.
“Volume constraint”
Check/uncheck for using a given maximum value of the mesh volume “Volume constraint (m3)”.
“Volume constraint (m3)”
Maximun accepted value of a mesh volume (m3). The value can be modified only if the “Volume constraint” parameter is checked.

SPPS Calculation parameters¶

“Active calculation of atmospheric absorption”
Enables calculation of atmospheric absorption.
“Active calculation of diffusion by fitting objects”
Enables calculation of calculation of diffusion by fitting objects.

Important

If fitting zones are enabled, by checking this option, it disables the calculation of all fitting zones. If you uncheck this option, the individual configuration of each fitting zone is preserved.
“Active calculation of direct field only”
Enables calculation of direct field only. There is no calculation of the reverberant field.

Astuce

This can be useful if you want to realize a first calculation, as a reference, of the direct field at receivers. The second calculation (direct and reverberant fields) can thus be calculated and compared to the direct field (first calculation).
“Active calculation transmission”
Enables calculation of transmission through walls.
“Calculation method”
Selects the calculation method.
“Random”
Select the Random method.

“Energetic”
Select the Energetic method.
“Echogram per source”
Check to calculation an echogram for each sound source, for a given receiver. If uncheck, a global echogram is calculated by summing all source contributions.
“Export surface receivers for each frequency band”
Check to export the surface receiver results, for each frequency band. If uncheck, only the global value is exported.
“Limit value of the particle extinction: ratio 10^n”
For the “Energetic” mode only. It defines a limit value of the particle energy. If the decrease of the particle energy is less than this value (i.e. the particle energy is very low), the particle is removed from the domain. For example, if n=60, it means that all particles whose energy will decreases to 60dB, will be removed.
“Number of sound particles per source”
Defines the number of sound particles that are generated by the source.

Avertissement

The computational time depends on the number of particles. If you increase the total number of particles, you drastically increase the computaional time.
“Number of sound particles per source (display)”
Defines the number of particles that are used for the particle animation.

Note

Most of time, you need to consider only few hundreds or thousands particles for the animation. Incerasing this number, will decrease the memory resources.
“Random initialization number”
Initialize the random number series. If you select a number that is different from “0”, the random number series will always be the same. The starting number of the random number series will depend on the number you will consider for this parameter.

Avertissement

In a multithread simulation, I-Simpa/SPPS can not control the generation of random numbers. It means that this paremeter will have no effect. Multithread simulation occurs when several frequency bands are considered in the simulation. To avoid multithreading, consider only one frequency band calculation.
“Receiver radius (m)”
Defines the receiver radius (in m).
“Simulation length (s)”
Defines the duration (in s) of the simulation.
“Surface receiver export”
Select the kind of results that is exported.
“Soundmap: intensity”
Intensity level (in dB).

“Soundmap: SPL”
Sound pressure level (in dB).
“Time step (s)”
Time step (in s) for the calculation.

Computational time optimization¶

The computationnal time depends mainly of the Number of sound particles per source. Thus, in the SPPS code, each sound particle is followed, at each “Time step” during its propagation inside the 3D domain, experiencing absorption, reflection, diffusion… and so on, during the “Simulation length” and/or untill the particles disapears when its energy is to small.

Considering a small number of sound particles may not produced relevant results to proceed an interesting acouctic analazis of the 3D model. Thus, it is necessary to consider a large number of sound particles. Assigning the good value for large is difficult and depends mainly on the scene size and the absorbent nature of the scene (surface absorption and volume absorption).

Few recommandations to evaluate the computationnal time:

the number of sound particles defined in SPPS (“Number of sound particles per source” parameter) is defined for each sound source. Considering N sound particles per source and M sound sources will generate N x M sound particles in the domain;
one calculation is done for each frequency band: considering F frequency bands will be equivalent to a calculation with F x N sound particles for one source (or F x N x M for M sources). Note that, by default, the computation is paralleleized on the processor core, for each frequency band (a frequency band for a given core). So the increase of computional time with the nimber of frequency band is not linear;
in the “Energetic” mode, each sound particle is “alive” during its propagation untill its energy is below a ratio of the initial energy (see “‘”Limit value of the particle extinction: ratio 10^n” parameter). Increasing n will keep the sound particles longer in the domain, which increases the computational time;
in the “Random” mode, each physical phenomena (absorption, diffusion) is applied by considering probabilistic approaches. Using this mode, the computational time is drastically decreased, but the quality of the results is aslo decrease. It is suggested to consider the “Random” mode at the initial step of the study, and then to change to the “Energetic” mode in order to obtain the final result.

SPPS Results¶

All the results are displayed in the Results tab, following a specific `Tree structure`_. The content of the tree structure depends of the elements defined in the Scene tab, and of additionnal processes execute on the result files (such as for creating room acoustics parameters).

Comments:

All folders and files in the tree results can be renamed. A default name is created at the end of the calculation process.
Some folders may be repeated several times (for example, as many times as (AMTA) there are Punctual receivers)

❙— 📁 SPPS [Root folder]

❙— 📁 Date_folder [folder; AMTA Calculations]

❙— 📁 Intensity animation [folder]

❙— 📁 Frequency folder [folder; AMTA Frequencies]

❙— 📄 Intensity [file]

❙— 📁 Punctual receivers [folder]

❙— 📁 Punctual receiver name [folder; AMTA Punctual receivers]

❙— 📄 Advanced sound level [file]

❙— 📄 Punctual receiver intensity [file]

❙— 📄 Acoustics parameters [file; see]

❙— 📄 Advanced acoustics parameters [file]

❙— 📄 Schroeder curves [file]

❙— 📄 Sound level [file]

❙— 📄 Sound level per source [file]

❙— 📁 Surface receivers [folder]

❙— 📁 Frequency [folder; AMTA Frequencies]

❙— 📄 Sound level [file]

❙— 📁 Global [folder]

❙— 📄 Sound level [file]

❙— 📄 SPPS particle statistics [file]

❙— 📄 Total energy [file]

❙— 📄 config [file]

❙— 📄 projet_config [file]

In addition to classical room `Acoustics parameters`_, some `Advanced acoustics parameters`_ can also be calculated. The calculation of this advanced room acoustics parameters needs specific calculation of sound levels at a punctual receiver.

This Advanced sound level .gap file display the temporal evolution of the impulse response, for each frequency band, as a data table, weihgted by \(\cos \theta\) (LFC and LG) and \(\cos^2 \theta\) (LF and LG).

Given the nature of the Sound level .recp file (i.e. an echogram), the contextual menu that is associated to this Sound level .recp file allows to calculate several room acoustic parameters:

Sound Pressure Level (SPL) in dB
Sound Pressure Level (SPL) in dB(A)
Clarity C (in dB)
Definition D (in %)
Central Time Ts (in ms)
Reverberation time RT (in s)
Early decay time EDT (in s)
Stage Support ST (in dB)

Several parameters can be given by the user in order to calculate user-values of some room acoustics parameters:

Clarity: fix the value of the temporal limit of integration, usually 50 ms
Definition: fix the value of the temporal limit of integration, usually 50 ms
Reverberation time: fix the value of the sound level limit of integration, usually 30dB

Astuce

Multiple calculations are allowed for each paremeter, by using the semicolon “;” between parameters.

After the calculation parameters, two files are created in the corresponding folder:

“Acoustic parameters”
This file provides access to the room acoustics parameters in the form of a data table.
The parameters are given for each frequency band of interest.

When allowed, the Global value (i.e. the sum of all frequency bands) is calculated and displayed at the bottom of each column.

When allowed, the Average value (i.e. the mean value on all frequency bands) is calculated and displayed at the bottom of each column.

In addition to classical room `Acoustics parameters`_, some advanced parameters are also calculated, and displayed in the Advanced sound level file.

The contextual menu that is associated to sound level” file allows to calculate several room acoustic parameters:

Early lateral energy fraction LFC (in %)
Early lateral energy fraction LF (in %)
Early lateral energy LF (in dB)
Strength G (in dB)

Data display:

The Global value (i.e. the sum of all frequency bands) is calculated and displayed at the bottom of each column.
The Total value (i.e. the sum of all time step) is calculated and displayed at the end of each row.

Several parameters can be given by the user in order to calculate user-values of advanced parameters:

LF: fix the value of the temporal limit of integration, usually 80 ms
LFC: fix the value of the temporal limit of integration, usually 80 ms

Astuce

Multiple calculations are allowed for each paremeter, by using the semicolon “;” between parameters.

It displays the temporal evolution of the Schroeder’s curves [Sch65], for each frequency band, as a data table.

Astuce

User can create charts for representing data from the data table. See charts creation

Double left click on a Sound level .recp file open a new winodw with three tabs

“Sound Level SPL (dB)” tab
It contains the temporal evolution of the quantity, for each frequency band, as a data table.
This tab is opened by default.

The values are represented in sound pressure levels (SPL).

The Global value (i.e. the sum of all frequency bands) is calculated and displayed at the bottom of each column.

The Total value (i.e. the sum of all time step) is calculated and displayed at the end of each row.
“Sound Level SPL (dB)” tab
It provides a graphic display of the Global value.
The temporal evolution of the Global value is displayed, as an echogram.

The cumulative quantity of the Global value is displayed, according to the Schroeder’s backward integration [Sch65].
“Spectrum” tab
It displays a spectrum at the punctual receiver.

Double right click on a Sound level .recp file open a contextual menu that allows to calculate `Acoustics parameters`_.

This file contains the sound level and the spectrum per sound source. Double left click on a .recps file open a new winodw with two tabs:

“Sound Level per source, SPL (dB)” tab
It contains the sound level per source and f each frequency band, as a data table.
This tab is opened by default.

The values are represented in sound pressure levels (SPL).

The Global value (i.e. the sum of all frequency bands) is calculated and displayed at the bottom of each column.

The Total value (i.e. the sum of all time step) is calculated and displayed at the end of each row.
“Spectrum” tab
It provides a graphic display of the spectrum contribution for each sound source.

A Surface sound level .csbin file contains the temporal evolution of a quantity that represents an acoustic intensity on a surface.

Depending of the calculation parameters, one can obtain, for each surface receiver, by default, on Global value (in the “Global” folder) and, in addition, the result for each frequency band in a corresponding folder.

A right click on a surface receiver file opens the contextual menu, with specific actions:

“Acoustic parameters”
Allows to compute relevant room acoustics parameters on the surface. Depending of the selection, it creates additional files within the corresponding folder.
Clarity C (in dB)

Definition D (in %)

Central Time Ts (in ms)

Reverberation time RT (in s)

Early decay time EDT (in s)

Stage Support ST (in dB)
“Load animation”
It allows to represent the spatial variation of the indicators that is selected. If the indicators contains some time dependent value, it can displayed an animation. On can interact on the animation with the “Simulation” toolbar.
“Instantaneous value”
Show the value of the given indicator at each time step.

“Cumulative instantaneous value”
Show the value of the given indicator at each time step, by cumulating all past steps.

“Total value”
Show the total value of the given indicator. No animation.

Using TCR within I-Simpa¶

TCR is already embedded in I-Simpa. Follow the next instructions to run a calculation with the TCR code in I-Simpa.

Double left click on the TCR calculation code in I-Simpa to display all calculation parameters:

Meshing, for the meshing configuration
TCR Calculation parameters for the calculation parameters

Right click on the selected calculation code to display all possible actions:

Run calculation
Job list

Meshing¶

Some calculation codes may require a meshing of the domain (SPPS for example). I-Simpa used the TetGen meshing code (A Quality Tetrahedral Mesh Generator and a 3D Delaunay Triangulator). See the documentation for more information.

Within I-Simpa, TetGen can be paramatrized:

“Test mesh topology”
Check/uncheck for activate the debug mode of TetGen (debug mode).

Avertissement

With the debug mode, the meshing is not realized.
“Additional parameters”
Add parameters to the TetGen default parameters.
“Radius/Edge ratio”
Defines the ratio between the radius of the sphere that would contain a mesh and the lenght of the mesh. This parameter could be useful in order to avoid long meshes.
“Scene correction before meshing”
Check/uncheck for trying to repair the 3D scene if possible.
“User-defined paramters”
Defines new parameters by replacing default parameters.
“Surface receiver constraint”.
Check/uncheck for using a given value of the mesh surface “Surface receiver constraint (m²)”.
“Surface receiver constraint (m²)”
Maximun accepted value of the mesh surface (m²) for a surface receiver. The value can be modified only if the “Surface receiver constraint” parameter is checked.
“Volume constraint”
Check/uncheck for using a given maximum value of the mesh volume “Volume constraint (m3)”.
“Volume constraint (m3)”
Maximun accepted value of a mesh volume (m3). The value can be modified only if the “Volume constraint” parameter is checked.

TCR Calculation parameters¶

“Active calculation of atmospheric absorption”
Enables calculation of atmospheric absorption.
“Export surface receivers for each frequency band”
Check to export the surface receiver results, for each frequency band. If uncheck, only the global value is exported.

Run calculation¶

Starts the calculation with the selected calculation code.

Job list¶

Instead of running the calculation, manually one after the other, you can create a list of calculation and, thus, run all calculations at once.

Important

To use a job list, you have to create a specific project for each job. If you keep the same project, but if you change only some parameters, you will repeat exactly the same calculation.

“Add calculation in the job list”
Add the calculation of the given project in the job list.
“Clear job list”
Clear the job list.
“Run job list”
Run the job list.
“Show job list”
Show the job list in the tab “Messages” of the “Console”.

“Results” tab¶

The “Results” tab contains all results produced by the calculation codes. When a project is loaded into I-Simpa the outcome data are organized as a tree structure that exactly correspond to the folder/files tree on the hard disk (i.e. the physical tree). It is possible to directly access to the contents of a folder from the associated contextual menu, by choosing the “Open folder” option. If changes are made in the physical tree, it is possible to refresh the results true by setting the action “Refresh folder”.

Avertissement

Deleting a folder or a file from the I-Simpa interface or from an extern file explorer is definitive.

The results of the calculations are sequentially added to the “Results” tree with a folder name that is automatically generated from the date of the calculation (the name can be modified by the user). For each calculation, two XML files are automatically added to the results folder:

the config.xml file is generated by I-Simpa and contains all the information that are needed for the calculation (according to the calculation code used).
the projet_config.xml file contains all information in the 3 tabs “Scene”, “Calculation” and “Results”. This file can be used as a “memory” of the calculation (archive).

In addition, each calculation codes generates specific files that can be interpreted by I-Simpa, depending of their format (with specific contents and file extensions).

For more information, see the “Results” section of each calculation code (in the documentation):

For the SPPS code : see section SPPS Results

File formats¶

I-Simpa can interpret two types of file:

File formats recognized by the Operating System, such as txt, xml, html, pdf… for example. Double left click on the file starts the associated program within the operating system.
Native I-Simpa files: these file are created by the calculation code and that can be associated with specific actions and treatments within I-Simpa.
- File .recp
  Punctual receiver file data type
- File .gap
  Punctual receiver file data type
- File .csbin
  Surface receiver file type
- File .gabe
  Tabulated data file
- File .rpi
  Animated intensity file
- File .pbin
  Animated data file