Skip to content

Receiver

Receiver points are distinct locations where the sound level is calculated. The level calculation for receivers is started either via the command Calc on the Calculation menu or by clicking the pocket calculator symbol on the toolbar.

After calculation select the respective evaluation parameter from the list box on the toolbar top display the results in the graphics.

Compared to grid calculations (see Receiver Grid) the partial levels are stored for all receiver points. Moreover, a detailed calculation protocol can be produced for receiver points showing all relevant intermediate values (see chapter Calculation Protocol).

For receivers, the acoustic rays can be displayed up to the selected order of reflection provided the option „Generate Rays“ has been activated on the dialog Receiver prior to the calculation.

Dialog Receiver

Land Use/Standard Value

When a limiting level or standard level is specified on the dialog Receiver (either by selection of a type of land use or entering values) it can be evaluated after a calculation right from the graphics whether this level has been respected or exceeded. In case of excess the receiver point is displayed in red on the graphics.

Note

The color being used for receivers can alternatively be defined via dialog Appearance using a formula.

Specifying Limiting Values

Limiting levels or standard levels can be specified in two ways.

Option "Land Use"

By default, the option "Determine from Areas of Land Use" is activated. In this case, the limiting or standard levels result from the type of land use and the selected type of noise ("Use Standard Levels for"). The types of land use are defined on the menu Options|Land Use (see Type of Land Use).

When the option "Determine from Areas of Land Use" is deactivated a type of land use can be selected locally. After calculation, the respective limiting or standard level is displayed.

Option "Standard Value"

When this option is selected a limiting or standard value for each evaluation parameter can be entered directly.

Sound Pressure Level

Here the receiver level for each evaluation parameter specified is displayed (see Evaluation Parameters Tab). Either the selection „Type“ or the input for „Name“ is used as a designation depending whether option „Name“ has been activated or not.

Excess Level

Here the excess level value for each evaluation parameter is displayed.

Per default, the receiver symbol in the graphics changes to red if the limiting value is exceeded for the selected evaluation parameter. Alternatively, a different color may be used in a formula (see Object Appearance).

Option "Generate Rays (as Aux. Polygons)"

If this option is activated prior to the calculation at receivers the sound rays up to the selected order of reflection are displayed using auxiliary polygons (see also Displaying Sound Rays). The ID of the auxiliary polygons shows the partial level for the first evaluation parameter and the reflection order.

Note

In case the first evaluation parameter is a mixed level (e.g. Lden) the displayed of Ld in the ray/s is enforced.

The rays are deleted after having deactivated this option and recalculation.

components of the polygon’s ID:
  • RAY: identification as a ray
  • 616: partial level Day 61.6 dB(A)
  • 00: direct path (0th order)
    		•  components of the polygon’s ID:
  • RAY: identification as a ray
  • 439: partial level Day 43.9 dB(A)
  • 01S: ray 1st order, S: screened (i.e. ray is diffracted by at least one obstacle)
    		•

    Dialog Aux. Polygon, button „Protocol“

    This button appears only when a calculation protocol was generated (see Calculation Protocol). The subsequent dialog Protocol shows the calculation results per ray. In case the option „Minimum Value for Lr“ is activated (see chapter 6.4), this will be ignored here.

    Note

    Since the rays are auxiliary polygons they are not shown on 3D-Special view by default (see 3D Tab). Activate the option „Show in 3D“ on the „3D“ tab of the object type „Aux. Polygon“ (see Object Appearance) to display them.

    Level Spectrum (dB)

    When the emission of sources is specified by spectra the dialog Receiver gets expanded in order to display the resulting octave level spectrum for the selected evaluation parameters.

    dialog Receiver (type: spectrum in octave bands) dialog Receiver (type: spectrum in octave and third-octave bands)

    Note the following remarks regarding the displayed octave or third-octave level spectrum/spectra:

    • The displayed A-weighted receiver level/s contains the partial levels of all emission types: those of the sources with A-weighted emission, as well as those with an emission spectrum in octaves or in third-octaves bands.
    • The octave level spectrum/spectra displayed contains the partial levels of all sources with an emission spectrum in octaves or in third-octaves.
    • The third-octave level spectrum/spectra displayed contains the partial levels of the sources with an emission spectrum in thirds-octaves only.

    (see also table below)

    emission typesource ... is included in ...
    A-weighted receiver level spectrum in octave bands spectrum in third-octave bands
    A-weighted emission + - -
    emission in octave bands + + -
    emission in third-octave bands + + +
    • When a level in an octave band of a single active source is missing, this frequency band will not be displayed on table "Level Spectrum".
    • The weighting for octave bands can be specified via menu Options|Miscellaneous (see Miscellaneous).

    Buttons

    Geometry

    see Object’s Geometry

    Partial Level

    Clicking this button displays the A-weighted partial levels or the octave level spectra of all sources contributing to the level at this specific receiver in the table Partial Level (see Partial Levels).

    Note

    Partial levels are not displayed in third-octave bands, even when such sources are present and activated.

    Note

    In addition, the table Partial Level on the Tables menu shows all A-weighted partial levels for all receiver points.

    AzB-Level

    This button is available with option FLG only.

    Directivity

    A directivity can be assigned to receivers via this button. Sound rays incident from different angles at the receiver‘s location are weighted by the selected directivity and added energetically.

    The selection of receiver directivity is made via the Directivity dialog (see Directivity at Industrial Sources, Directivity dialog). User-defined directivity is entered via the Directivity libraries (see User-defined Directivities).

    Entering receivers at a building’s facade

    In order to enter receivers at a distinct distance from a building’s facade, select the command Object Snap on the menu Options (see Object Snap). The default distance is 0,05 m.

    The generate receiver points for multiple storeys use the command Generate Floors (see Generate Floors in manual „Introduction to CadnaA“).

    Specifying the Precision of Levels

    By default, the receiver levels are displayed with a precision of one decimal. This can be changed via the CadnaA INI-file. Proceed as follows:

    • Close all CadnaA-main windows ().
    • Open the file CADNAA.INI and enter in section [Main] the following text line: dBOutPrec=X (with X: number of decimals).

    Note

    Regarding the location of the CadnaA INI-file see Installing CadnaA in the manual „Introduction to CadnaA“.

    This setting is relevant for dialog Receiver and for the table Partial Level.

    Dialog Receiver: Level with a precision of 2 decimals