Evaluation Parameters Tab
Evaluation Parameters tab
CadnaA offers a flexible approach to define the evaluation parameters to be calculated, such as individual levels (e.g. Ld, Ln) or level for combined periods (e.g. Lden, Lde), the uncertainty Sigma (for Day/Evening/Night) or for user-defined expressions. The following evaluation parameters can be selected by default:
- levels for individual daily periods D/E/N: Ld, Le, Ln
- levels for combined daily periods („mixed levels“): Lden, Lde, Len, Ldn
- uncertainty for daily periods D/E/N: SigmaD, SigmaE, SigmaN (based on the specification of the standard deviation, see General Tab, Uncertainty)
- loudest hourly level in the daily periods D/E/N: L1hMaxD, L1hMaxE, L1hMaxN (based on a diurnal pattern of the source, see Common Input Data, Addressing Diurnal Patterns)
- maximum level for the daily periods D/E/N: LmaxD, LmaxE, LmaxN (based on the input of Delta-PWL/PWL‘/PWL“ D/E/N in the data of point, line and area sources, see Common Input Data, Maximum Level Lmax), and
- relevant exterior noise level acc. to DIN 4109, version 2016 or 2018, part 1. A detailed explanation of the calculation is available in the German version of this documentation.
- formula expression „=f(x)“: total level or noise-type specific level, Day/ Evening/Night, single value or spectrum, total or in octaves, third-octaves, linear/A-/B-/C- or D-weighted. Furthermore, attributes for evaluation parameters are available offering to define evaluation parameters using a single or more combined reference time periods in a flexible way (see Attributes for Evaluation Parameters).Formula expressions can be defined using the CadnaA specific operators (see Chapter 5 - Operators & Functions in the manual „Attributes, Variables, and Keywords“).
Furthermore, the following aircraft noise specific levels and evaluation parameters are available (requires option FLG):
- the number of events (e.g. flight movements) above a threshold level: NATd, NATe, NATn,
- the uncertainty for the number of events (e.g. flight movements) above a threshold level: SigmaNATd, SigmaNATe, SigmaNATn,
- the resulting level of the maximum level evaluation for aircraft noise: FlgStatD/E/N,
- the standard deviations of the resulting level of the maximum level evaluation for aircraft noise: SigFlgStatD/E/N, and
- the so-called „effect related substitute level“ (see Multiple Source Effect) according to the VDI guideline 3722-2 3722-13 for the evaluation parameters Lden (DEN) and Ln (Night).
As long as no formula expression f(x) is used to exclude certain noise types from calculation all selected evaluation parameters are calculated including all types of sources, provided these sources are active. The result levels are calculated for up to evaluation parameters at individual receivers or facade points (using the building evaluation symbol), as well as on the horizontal or vertical grids (besides the ground).
Dialog options
List Box „Type“
Select from the list box „Type“ the evaluation parameter to calculate. In dialogs and tables showing calculation results (e.g. on the dialog Receiver) up to four evaluation parameters are displayed.
Example: The evaluation parameter for calculation according to the EU Environmental Noise Directive are the day-evening-night index Lden and the night index Ln.
In formulas or expressions that attribute names LP1 to LP4 are used for establishing a reference to the evaluation parameters (see Table Object Attributes in the manual „Attributes, Variables, and Keywords“). By default, the daytime level Ld and the nighttime level Ln are set.
Input Box „Name“
After activation of the input box „Name“ a user-defined expression (alias name) can be entered for the selected evaluation parameter (e.g. „Day“) which will be displayed instead of the name selected on the list box „Type“.
Dialog Receiver showing three evaluation parameters, for LP1 an alias name has been entered
Input Box „Unit“
Additionally in the box „Unit“ you may enter an identifying item (e.g. dB(A) or sigma) which will also be displayed if the check box is activated. Otherwise, „dB“ is displayed for unit. In particular, this option is useful in conjunction with a formula expression f(x) (see below), since by a formula any kind of result can be generated, the unit of which is not necessarily more expressed in decibels.
Input Box „Expression“
After selecting the formula symbol „=f(x)“ from the list box „Type“ a user-defined formula expression or a predefined expressions (see double arrow 
) can be selected or entered. In formula expressions the CadnaA specific operators can be used (see Table Object Attributes in the manual „Attributes, Variables, and Keywords"). known expressions return an invalid value (-88 dB).
The expression „indd“ calculates the A-weighted level Lday just for industry sources.
Clicking the double arrow opens a cascading list of predefined expressions. Select the corresponding parameter from the list.
Access to third-octave levels
For formula expressions, the user interface only allows direct access to octave levels from 31 to 8000 Hz. By editing the expressions third-octave levels can be accessed. Examples:
- totd_t01: total level Day of third-octave No. 01 (31 Hz)
- totd_t31: total level Day at third-octave center frequency 31 Hz
Note
Since the number 25 addresses both, a frequency or a band number, this should be avoided (band No. 25 refers to the third-octave at 8000 Hz).
Error Condition
In case an error occurs within a user-defined expression the value -88 will result for that evaluation parameter.
Notes for user-defined expressions
- The selections „Single Value“ and „Loudest Hour“ include all active sources or all active sources of a source group, with non-spectral and spectral emission.
- By contrast, the selections „Spectrum|Total (linear//A-/B-/C-/D-weighted)“ include the active sources or the active sources of a source group with spectral emission only.
Note
Both notes above cause that when having non-spectral and spectral sources in a project, a level difference occurs between the two above-mentioned selections (e.g. between the A-weighted sum level as „Single Value“ (totd) and the A-weighted sum level of the spectral sources only („Spectrum|Total|A-weighted“, totd_a).
- In case a mixed level shall be used as an evaluation parameter (e.g. „Lden+3 dB“ or „Lde_road-3dB“), it is always required to enter the entire formula because mixed levels are not available as predefined expressions.
- Conditions can be used in expressions (operator „iif“, see the subsequent example section). Note that just numerical expressions may be used in formulas. In particular, no strings can be used in a condition or as a result of a condition.
- Use just the parenthesis „()“ to define nested expressions. Other types of brackets meet the error condition.
- In order to separate variables in expressions just use the comma. Other separators (e.g. the semicolon) meet the error condition.
- Extra spaces within expressions are harmless and do not meet the error condition. By contrast no spaces are allowed between an operator and its opening parenthesis [thus „iif(...), not „iif_(...) with „_“ representing the space].
Examples for expressions
| Expression | Remarks |
| totd+3 | addition of 3 dB to the total level Day |
| strd++schd | energetic summation of level Road Day and level Railroad Day |
| totn_2l++totn_3l++totn_4l | energetic summation of the linear total octave level from 125, 250 and 500 Hz (octave-No. 2, 3 and 4) |
| indd-strd | level difference between the level Industry Day and Road Day |
| totd+1.65*sigmad | upper limit of the Daytime-level at 95% single-sided confidence interval („level that is not exceeded at a statistical confidence level of 95%“) |
| iif(totd>50, totd, 0) | if the total level Day > 50 dB it will be displayed, otherwise zero |
| iif(totd>50, 0, totd) | if the total level Day > 50 dB zero, otherwise the total level Day will be displayed |
| flgd + 3*sigmad | aircraft noise level Day + 3 * standard deviation Day |
| flgn + 3*sigman | aircraft noise level Night + 3 * standard deviation Night |
| natn + 3*sigmanatn | number of exceedances of the threshold level for aircraft noise Night + 3 * standard deviation of the number of exceedances Night NOTE - The threshold level for NATs (dB) is specified on the „Aircraft“ tab. |
Attributes for Evaluation Parameters
Attributes for evaluation parameters can be used to perform calculations for arbitrary reference time periods, in particular in conjunction with diurnal patterns (see Diurnal Patterns). This type of calculations either cannot be performed with the pre-defined evaluation parameters or, at least, cannot be performed in a single calculation run. In Germany, for example, the noise impact from sporting facilities on Sundays or public holidays is limited for three distinct time periods which must be evaluated separately when checking for compliance 18BImSchV-1991. These types of calculations are possible with attributes for evaluation parameters in a single calculation run (for a maximum of four evaluation parameters).
Defining the reference time period (using 24h format)
There are three ways to define the reference time period.
| No. | Refer. Time Period | Syntax |
| 1 | a single hour | xxxmh11 („mh“ stands for „multiple hours“) with |
| Examples: |
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| 2 | range of hours | xxxmh11_22 with |
| Examples: also when passing mid-night: |
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| 3 | arbitrary reference time period/s | xxxmhyyyyyy with |
| Examples: |
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Example
Path: Examples\Configuration\Evaluation Parameters\calculation HEX for eval. parameters mh.xlsx
By the XLSX file referenced, the hexadecimal figure to be entered can be generated based on the specified reference time range. Alternatively, this can be achieved using the „Calculator“ application, which is a standard application on Windows systems (using the calculation type „Programmer“).
Note
When using attributes for evaluation parameters the settings for the „Allocation Hours-Periods“ and the penalties „Day/Evening/Night“ on the „Reference Time“ tab (see Reference Time Tab) are ignored.
Application
Please find here referenced two files showing on how to define three distinct time periods for evaluation using attributes for evaluation parameters.
Example
Path: Examples\Configuration\Evaluation Parameters\3 eval. parameters for three time periods.cna
Example
Path: Examples\Configuration\Evaluation Parameters\3 eval. parameters for three time periods - HEX.cna
Mixed levels and Attributes for Evaluation Parameters
In principle, also mixed levels can be defined, also in conjunction with penalties. This, however, requires that all time periods and - if any - penalties are included in a formula f(x).
Example
Path: Examples\Configuration\Evaluation Parameters\Lde using eval. parameter attributes.cna
For example, to define the mixed level Day-Evening Lde (period D covering 7-20 hrs (=13 hours) and period E covering 6-7 hrs and 20-22 hrs (= 3 h)) by using attributes for evaluation parameters, also the following expressions can be used:
- using the variants „single hour“ and „range of hours“:
10*log10((1/16)*(13*exp10(totmh07_19/10)+exp10((totmh06+6)/10)+2*exp10((totmh20_21+6)/10)))
or
- using the variants „arbitrary reference time period/s“:
10*log10((1/16)*(13*exp10(totmh0FFF80/10)+3*exp10((totmh300040+6)/10)))
DIN 4109 Version
only available in German
Adjusting the configuration
Regarding the option „Compatibility Mode for Industry“ on the „Evaluation Parameters“ tab of former releases of CadnaA see Adjustment of the Configuration.