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Adding Sources and Receivers

Under the "Sources / Receivers" tab in the sidebar you can define sources, point receivers and surface receivers.

Placing a source in the model will define where in the model sound will be emitted from. On the other hand, placing a receiver lets you define where to capture the sound from.

For each source, point receiver and surface receiver you can:

  • Select them in the viewport and edit their placement, or adjust the coordinates in the sidepanel.
  • Rename them by clicking the "pencil" icon next to the point/surface name when hovering over it with the cursor.
  • Remove them by clicking the "trashcan" icon next to the point/surface name when hovering over it with the cursor.

You can collapse the sources or Receivers sections by clicking the arrow next to each section, creating more space to view either one.


A source or receiver can be moved by using the controller that appears in the viewport. The controller has arrows and planes that you can click and drag to adjust the location of your source or receiver.


To add a new source, click the ’+’ button in the upper right corner in the Sources section. You can create up to 10 sources.

Sources can have different properties like coordinates and source definition. For each source in the simulation, the simulation engine computes a separate set of results. Therefore the cost of each simulation scales with the number of sources in the simulation.

The newly created source will appear as a green dot in the viewport. The source can be selected by clicking the source row or by clicking the corresponding green dot in the viewport. The default source definition assigned to new sources is an Omni source.

Sources can be moved by using the controller that appears in the viewport or by typing in coordinates (e.g. "x: 1, y: 0.5, z: 1.7"). Make sure that the source is placed inside the model and at a distance no smaller than 0.5 meters away from any surface. If your sources or receivers are in an invalid position they will turn red and you will not be able to run your simulation.

Source 2 is too close to a surface.

Source definition library

To change the source definition for a source, click on the assigned source definition in the upper right corner of a source row. This will open the Source definition library to the left of the sidepanel.

A library of source definitions comes included, however you can also upload your own source definition.

Source definitions are split into 3 types: Amplified, Natural and Other. With each type containing a unique set of categories.

It is possible search the library and to filter by the 3 types and manufacturers or categories and search.

You can also utilize the built in filters for Default, Organization and Created by me.

Source definition properties such as directivity pattern and SPL on axis at 1m are shown at the bottom of the library.

Source settings

To edit source properties, click on the "settings" icon next to the source coordinates. This will open a popup called Source settings.

In the Source settings popup, you can also assign a source definition and view details about the selected source.


This source definition will only be applied to the GA solver.


We are currently working on upgrading our source modelling capabilities, which will included features such as setting the source levels and enabling directive wave-based sources. Check out our feature roadmap for more details.

From here you can also assign source definitions, view their directivity pattern, SPL on axis response at 1m and apply EQ.


In some cases, values of the on axis response in octave bands are colored orange. This is to highlight that this value is extrapolated from the source information and was not a measured value. Treble's simulation platform always needs the full bandwidth on axis response. The full on axis response can be viewed as a plot in 1/3 octave bands resolution.

Directive sources

If you have selected a directive source (e.g. Speech), the panel will show the orientation as well as the location. When a directive source is selected, a small black arrow will be shown from the controller in the viewport to help you orient the source.

You can edit the orientation of the directive source using the angle input shown in degrees for:

  • Azimuth. The azimuth angle will rotate the arrow counterclockwise on the XY plane, starting from the X axis.
  • Elevation. The elevation angle starts from 0 and has a range between -90 (-Z) and +90 (Z) degrees.
  • Rotation. The counterclockwise rotation around the front facing axis (0 to 360 degrees)
EQ and overall Gain

You can edit the source by adding gain to octave bands to reach the desired levels. This will always be applied to the spectrum and impulse response of the source.

Correcting the IR with on-axis response

The "correct IR with on-axis SPL" toggle can be seen in the Source settings pop up, on the bottom middle. Here.

All sources are simulated with a flat on axis response and a given source definition. This toggle enables correcting the Impulse response with the 1/3 octave band response and the added gain.

Note that the Frequency Response is always corrected with the on axis response.

If you wants to auralize speech using a speech source, then the source of the speech should not be applied to the IR, since that spectrum will inherently come from the speech source signal.


A receiver represents where you want to be storing the results of the simulation. It acts as a "virtual microphone" that you place inside the space at the location where you want to measure or listen to the result.

There are two types of receivers available: Point receivers and Surface receivers, which both are added in a similar manner to the sources. To add a new receiver, select the type you want (point or surface) and click the ’+’ button. You can create up to 100 point receivers and have up to 300 points in total for surface receivers.

Point receivers

The point receivers are represented by blue dots in the viewport. To find a specific point receiver, click the receiver row in the Receivers section and it will be selected in the viewport.

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Receivers should be placed inside the model, at least 0.15 meters away from any surface and 0.5 meters away from any source. A receiver will turn red in the viewport if it has an invalid position.


For each point receiver, spatial (second order ambisonics) impulse responses will be automatically created, which is what is used in the spatial audio processing in the Auralization.

Load receivers from file

It is also possible to read multiple receiver coordinates from a text file by pressing the three dots and selecting Load from file. The receiver coordinate values must be separated with commas and each receiver should be in separate lines.

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Surface receivers

The surface receiver creates a grid of point receivers sampled in a cartesian grid across the surface, where each point receivers is placed at the center of each square on the surface. For each square, all acoustic parameters are calculated, but not the impulse response or the spatial impulse response. The surface receivers are identified with the grey diamond icon in the viewport and sidebar.

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There is exactly one point receiver per square in the defined surface receiver. For each square, all parameters are calculated.

For each surface receiver, define the length and width (in meters) and place it in the model by moving and rotating it. If a part of the surface is placed outside of the model, the invalid points of the surface the will just be disabled. A surface needs to contain at least 2 points.

The orientation of the surface receiver uses the same rotation principles as descrived in Directive Source


It is possible to use the controller for setting the position of the surface, but the orientation and size has to be set numerically using the sidebar.

The final input is spacing. This defines the distance (in meters) between the points in the surface receiver and therefore, the density of the underlying receivers in the surface. Spacing can only be set in fixed steps meaning the length and width of the grid may change slightly when adjusting the spacing of the grid.


Simulations will take more time if you increase the density of each surface receiver. It is therefore good practice to keep an eye on the estimated simulation time before starting your simulation.

It is possible to hide the surface receiver in the viewport by clicking the ‘eye’ icon on the right side of the input parameters. To delete a surface receiver, click on the ‘trash can’ icon to the right.

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Work in progress