P&K 2714
Program description
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Dispersion calculations for noise according to the Guidelines
ISO 9613-2 (VDI 2714), VDI 2571, VDI 2720, RLS-90 and SCHALL 03
Index
1. Introduction
1.1 Sound technical background
1.2 Installation
1.3 Projects
1.4 Integrated help and manual
2. Input data
2.1 Dialogs
2.2 Sources
2.3 Obstacles
2.4 Receptor points
2.5 Spectrums
2.6 Variants
3. Spectrums catalog and generators
3.1 Catalog manager
3.2 Catalog tables
3.3 Calculation forms
3.4 Relative spectrum
3.5 RLS-90 and SCHALL 03
4. Analysis
4.1 Propagation calculation
4.2 Sound power of the source (Lw)
4.3 Solid angle index (Ko)
4.4 Absorption of sound by the atmosphere (Dl)
4.5 Ground/Meteorology attenuation (Dbm)
4.6 Vegetation/Development attenuation (Ddg)
4.7 Insertion attenuation (De)
7.1 Scaling
7.2 Legend
7.3 Object illustration settings
7.4 Illustration of numbers
7.5 Illustration of colored shapes
7.6 Illustration of Isolines
Appendix
1. Introduction
With P&K 2714 we offer a PC program to carry out dispersion calculations for noise according to the following guidelines:
The effects of almost any number of noise sources (facade, outside and line sources) to the surrounding area can be determined for planning and consulting of sound-technical projects. The phenomena as reflection, dispersion and diffraction on obstacles (maximal 1,000 cuboid objects) as well as on the ground are taken into account automatically.
All calculations are carried out in the octave band or with weighted levels.
The program differentiates between facade, outside and line sources. The sound power for facade sources is determined by the interior level, the area and the facade material. For outside sources, the sound power is defined directly. The noise emission of line sources is defined by the emission level (Lm,E). The source coordinates can be referred to one of the obstacles (building), though they can be moved with each other. Switches for source data allow the calculation of three variants (e.g. day level, night level and peak level) simultaneously. This allows Calculation of the day-evening-night level Lden according to the DIRECTIVE 2002/49/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 25 June 2002 relating to the assessment and management of environmental noise.
The result table demonstrates the sound pressure in the frequency band and the dominant source for each receptor point. For verification of the calculation, an analysis independent of the prognosis can be carried out for selected sources and receptor points (receivers) . The analysis will produce detailed reports and a graphical illustration of the propagation paths.
An integrated spectrum generator calculates noise spectrums from technical data of various elements (e.g. steam throughput and temperature for a steam valve) or emission level (Lm,E) according to RLS-90 and Schall 03. In addition, access to spectrums catalogs for sound power, absorbing materials and hall internal levels are available.
Prognosticated noise levels can be illustrated in different diagrams (colored shapes, placed numbers or Isolines).
1.1 Sound technical background
Noise sources are characterized by sound power on a spot in a room. For sound radiating facade elements, this value is calculated according to VDI 2571 (page 5). Therefore the sound attenuation and the interior level have to be defined. The sound radiation of line sources is defined by the emission level (Lm,E) according to RLS-90 respectively. SCHALL 03 on a center point of a sufficiently small (relatively to the receiver) section.
A sound level (interior level, attenuation value, sound power level, emission level) can be entered either as a value or as a named reference to an entry in the spectrums list. An entered value replaces the definition in the spectrum (level in the frequency band or weighted level, according to calculation mode). The reference to the spectrum list is always necessary when calculating with a variable frequency band or variants, which are considered in the spectrums list only.
Up to 3 states of operation of a plant can be defined with variant switches. Such states, considering the requirements of TA Lärm, can be: daytime operation, nighttime operation and maximal nightly level. That means the gates which are only shut at night, are turned off during the daytime, or, if necessary, traffic noises are turned off at night, or, power plant valves are only turned on for determination of the peak ambient air concentration, otherwise they are turned off.
The interactions with obstacles on the sound path between source and receptor point have a decisive influence on the noise propagation outdoors. One part of these obstacles is considered as vegetation and development with a definable height and an exclusively absorbing effect. For noise paths within this layer, an absorbing coefficient (ISO 9613-2 (VDI 2714), page 6) is considered. Taking discrete obstacles into consideration, which are defined in the obstacle list as cuboids sitting on the ground, is much more laborious. These objects (equivalent to the phenomenon in the range of visible light) cause reflection and dispersion of the sound waves on surfaces (walls and ceiling) and diffraction on the edges.
To quantify the diffraction, the two shortest ways around and the shortest way over the obstacle as defined by the guideline VDI 2720 (Part 1, page 5-7) are calculated and the resulting screening attenuation are energetically subtracted from the insertion attenuation.
The reflection on the outside of the obstacles (walls and roof) and on the ground are considered in the program according to ISO 9613-2 (VDI 2714) (page 8). Therefore, for each obstacle and the floor a loss spectrum is definable. Low reflection losses are to be expected in case of sound-hard plane surfaces. For line sources, the ground reflections are already integrated in the algorithm of the guidelines RLS-90 and SCHALL 03 and for that reason they are not considered as additional image sources.
If the energy, directed to a surface, does not emit as reflection or is not destroyed by absorption (dispersion loss), it will propagate back into the room. The total power of the propagated sound (from the source view) is proportionally decreased to the solid angle by the propagation loss. The guideline ISO 9613-2 (VDI 2714), page 5, considers this phenomenon in form of the solid angle index, though, for the sake of simplicity the guideline assumes a divergence without loss and overall divergence rooms (half, quarter, eighth-room). P&K 2714 allows a more differentiated statement here. For line sources a solid angle index is not taken into account, because the guidelines do not provide such an index for line sources.
When estimating the dispersion loss and the reflection loss, it is to be considered that an area cannot be free of both losses at the same time. To get a feeling for possible constellations, the analogy to visible light will be helpful. A surface without reflection loss (such as a mirror) does not have a share of dispersion as a white surface does and vice versa.
1.2 Installation
Just start the installation program and follow instructions.
If desired, change the language in the menu Options.
The program can be started by executing pk_2714.exe. For simplification, a link to a user defined program group has been produced during the installation.
1.3 Projects
The parameter settings and results of an project are stored in a set of files with the same name, but with different extensions. After starting the program the project name defaults to NONAME.
Functions for all necessary handlings of the projects are available in the file manager:
| Open | In this form, projects can be chosen from a list. |
| New | Creates a new project with the name NONAME in which data can be entered. It can be saved under a new project name. |
| Save | Saves the current project |
| Save as | Saves the current project under a new name. |
| Select a project from a list of recently modified projects. |
For each project, a set of files with different extensions and the same name (the project) will be put into the current data path by the file manager and administered from there:
| *.IDP | Input data of the project (data of the previous program version can also be loaded) |
| *.IDR | Results of the calculation including the relevant input data (Sources are obstacle-transformed) |
| *.IDD | Results of the analysis including the relevant input data (Sources are obstacle-transformed) |
Catalogs can be saved in different files, which are to be loaded into the catalog manager beforehand. Different categories can be defined within a catalog file. The input can be filtered to ease input. The data types in use are:
| *.SPE | Catalogs with information about sound power, attenuation and interior level (The former catalogs with the extension SP1, SP2 and SP3 can be also loaded.) |
These project data and catalog files are complex binary files. Simple text files can be imported into or exported from the tables. See. Export / Import
The program includes the catalogs DAEMMUNG_2571.SPE and INNENRAUM_2571.SPE with information about sound attenuation and interior level measure defined in the guideline VDI 2571. These files can be found in the samples folder.
For an easy startup, one or more sample files are supplied with the program in the program folder. The program is designed to initially show the folders Sample(s) and/or Beispiel(e). This feature does not work on all windows versions, in such a case one has to navigate to the program folder (e.g. c:\Program Files\P&K\....).
1.4 Integrated help and manual
A context-sensitive help is integrated inside the program. It can be pulled up at any location in the form by pressing the function key "F1". In the help screen, if necessary, highlighted cross references (links) are interspersed, which, by clicking on them, provide more detailed information.
Under App-Config one can override the default Browser with a line like Browser=c:\....\firefox.exe. This is e.g. useful for Wine under Linux.
2. Input data
The input data to specify a sound propagation calculation is to be entered in forms and tables under the menu EDIT and are to be saved in a file for later access. The tabular input data are described in the following chapters.
The parameter form takes all non-tabular data. The multiple line text will be shown in the report and in the illustrations for further explanation. The shorter titles of the variants are used to create further headers information. Reflection and propagation on the ground are equivalent to the same phenomena on the obstacles and are defined in the chapters 4.2 and 4.3 of this manual.
see Parameter form
2.1 Dialogs
Operation within the forms
In the forms, the entries are made in form fields. With the keys Cursor up, Cursor down, Tab and Shift Tab or with the mouse the cursor can be moved over the fields. Cursor left and cursor right move the cursor character by character within a field.
Real numbers can be entered with a period or comma or as 1e-6 for 10-6. The error tone can be ignored on input, it is only triggered as a warning because 1e or 1e is not a valid number.
Posibly (if marked in the form) a selection list of discrete input values can be opened.
F1 provides context-sensitive help for a form field or the entire form and the integrated manual is accessible.
Click OK or CANCEL to leave the current form.
Also see: Calculator
Operation within the tables
The order and the width of all columns can be changed by clicking into a column header or between column headers and dragging as desired. This is practical if values are in a particular order, because Tab has to be pressed just once in order to reach the next column.
If the data in the columns are too wide to be displayed, then the symbols (in brackets) will be hidden in the column titles (e.g. Temperature (T0) ). Widening of the column will show that particular symbol.
The buttons "+" and "-" are used to insert or delete data sets. With the button "Dup" the current data set can be duplicated. The new row will become the last row in the table. This is useful if a data set is to be generated with minor difference to the current one. To insert a row, select the lower gray row before pressing the "+" button.
Individual fields, in which a selection is possible, are marked yellow. To activate the selection click once in a cell in order to select this; click a second time in order to activate the selection (no doubleclick).
With the cursor or Tab key, the focus can be moved between individual fields.
The illustrated section can be scrolled one row up or down by moving the cursor across the upper or lower edge of the table form.
Some tables can be sorted. With a right mouse button click into the considerable column, a Pull-Down Menu will be opened, and Sort Ascending or Sort Descending can be selected.
In some tables, a Row-Editor can be invoked. The Row-Editor shows one dataset only and can have more or less features then the grid dialog.
Sometimes single Columns can be imported via the Popup Menu. From the selected file, the values are taken and written to the position, from which the dialog was invoked. One value will be read per line from an ASCII file (includes CSV format) .
Sometimes single Columns can be imported via the Popup Menu. From the selected file, the values are taken and written to the position, from which the dialog was invoked. One value will be read per line from an ASCII file (includes CSV format) .
Some tables feature a search function. See Find in table
See: Calculator and Alter Column Values.
Filter
This feature allows to filter out a column with its value. Only rows with this value in the filtered column and not this column will be shown. The filter can be set to most of the columns (except when they are declared unique). All available column names are shown in the selector next to "Filter:". Once a column is selected, a corresponding value out of this column can be selected in the selector to the right of the equal sign. Filtering is accomplished on a text basis rather than on a value basis (e.g. 1.0 doesn't equal 1).
Using the filter feature will reorder the rows. Only columns, which are not defined as unique, can be selected. Some table can be sorted (Right Mouse Button Click into the column of regard.)
A filter might be active during import / export to exclude or include rows of data.
Table Import and Export
In most tables, data can be imported or exported with the buttons in the tool bar. The sequence of the columns and which columns are used, depends on the current column order and the current filter setting. With a button in the tool bar, a form can be opened which gives information about the current settings.
Single Columns can be imported via the Popup Menu. From the selected file, the values are taken and written to the position, from which the dialog was invoked. One value will be read per line from an ASCII file (includes CSV format) .
Available formats for import and export
| CSV | Columns are separate by commas (Comma Separated Values). If a text contains commas, it must be written in " " (Quotation marks). The decimal character is the point. Values can optionally contain an exponent (e.g.: 6.E-9), however no additional separators are allowed. |
| TXT | Columns are separated by spaces. If a text contains spaces, it must be written in ' ' (Apostrophe). The decimal character is the point. Values can optionally contain an exponent (e.g.: 6.E-9), however no additional separators are allowed. |
| Current Project Extension | Individual tables can be loaded from project files. The loaded table must fit logically into the project. The export creates a new project file, which contains only the exported table. |
| * | On selection of the file type [With Options (*.*)], the form Table Import Options will be opened, in which further parameters are available. |
The formats can be selected in the appropriate dialogs under the type of file. The filter function is switched off for other formats than CSV, TXT and *!
Preview
The tables can be viewed appealingly as an HTML-file by using the preview function. see Report function.
Also see: Calculator
Within the graphics
Most of the graphics can be zoomed; therefore a rectangle has to be opened with the mouse from the upper left corner to the lower right corner. To reset the zoom, a rectangle from the lower right corner to the upper left corner has to be opened with the mouse. Also the graphic can be moved; therefore the graphic is to be dragged with the right mouse button pressed.
Some dialogs can also be opened by clicking onto the axis, the legend, the title or double clicking the drawing area.
The button 
has to be down for all functions, which are activated by clicking into the drawing area.
Graphical illustrations on the screen can be printed with File/Print or the button 
.
The Export of Images can be done with 
. Images can also be copied to the clipboard with 
.
Setup (Layout, Export and Format)
A form in which more graphic parameters can be set. Functions for export and graphics formats are also in this form.
Alterations made in will not be saved automatically. In some illustrations it might be possible to save and load configuration changes under the file menu, but it might cause strange effects, because the configuration might not fit to the current illustration. Series, which are not needed in the current illustration and which are not automatically destroyed can be made inactive. Data are managed in so called Series. The configuration can be saved with or without data. The data are normally replaced with the current ones, despite this, sometimes it might still be important to save the data along with the configuration.
Modifications and settings in other forms or of the calculated data can overwrite made changes in Setup!
It is recommended to set the graphic type to the configuration to be loaded.
MAX
With the button MAX the scale settings are maximized.
ISO
The graphic can be illustrated isometrically by using the button ISO. This has to be repeated after changing the size of the graphic.
2.2 Sources
Within the context of this program, two types of point noise sources are to be differentiated. For so-called outside sources, the sound power is to be entered into the dialog directly (possibly in form of a spectrum), while the sound power for sound radiating facade elements of buildings (also doors, windows, openings) is determined by the interior level of the building area belonging to it and by the attenuation of the facade material according to the guideline VDI 2571. Details of the calculation can be found in the chapter 3.2 of this manual.
In addition, line sources associated with traffic can be included, according to the guidelines RLS-90 (for traffic) and SCHALL 03 (for railways). The calculation of levels on receivers then will be based on the emission levels (Lm,E) of a straight section of the line. The dispersion calculation for traffic sources differs in some details from the calculation for point sources (see chapter 4.1).
With the table editor, nearly any number of facade sources, such as outside sources and traffic sources, can be entered into the project file. These tables also can be created outside the program. In that case, they have to be configured as described in Import/Export.
The sources are identified through names and numbers in the report and in the illustrations. The names and numbers are derived from the index in the particular table and a capital letter (A for outside sources, F for facade sources and L for traffic sources).
If a number for a level (attenuation, power, emission or interior level) is entered instead of a reference to the spectrums list, it will replace all entries of the spectrum (in case of A-weighted calculations, it will also replace the column for the weighted levels).
The source coordinates can be referred to one of the obstacles (building), though they can be moved with each other.
2.3 Obstacles
With the table editor, maximal 1000 cuboid obstacles can be entered into the project file. This table can be also created outside the program, in which case they have to be configured as described in Import/Export.
Besides the geometry, each obstacle has sound technical surface qualities, which are characterized as reflection loss or dispersion loss. These characteristics are identical for each obstacle for the entire outer skin (including roof).
If a value is entered instead of a loss spectrum name, it will replace all entries of the spectrum (in case of A-weighted calculations, it will also replace the column for the weighted levels).
see Obstacles
2.4 Receptor points / receivers
The levels are calculated for all locations listed in Receptor Points. This list can be accessed with the table editor. This table can be also created outside the program, in which case they have to be configured as described in Import/Export.
For more comfortable handling, this program is equipped with a function for the generation of a circular point network with square meshes and uniform point heights.
This generator is set in a form, in which center point coordinates, radius of the area, mesh-size of the network, height of the receptor points and number of the receptor points per mesh are entered. Only meshes, which fit completely in the circular area, are created.
see Receptor point generate and edit
2.5 Spectrums
A maximum number of 1300 spectrums with maximal 8 supporting points in the octave band (for 63, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz) and additional A-weighted level can be entered into the project file with the table editor. This table can be also created outside the program, in which case they have to be configured as described in Import/Export.
Sound level (decibel values) of different types can be entered into the spectrums list. For calculations in the octave band, values are assigned to the midband frequencies. These values are, depending on the later operation, interpreted as sound power, attenuation, interior level, emission level, reflection loss or dispersion loss. Using A-weighted calculations, an additional column takes up the weighted level (A-weighted sound power or sound pressure and weighted attenuation), which is independent from the spectrum.
A name is assigned to each entry in the spectrums list by which it can be referenced (selected from a pull-down list) in the definition of sources and obstacles.
Explanations about the switches to control the variants can be found in the following chapter.
see Spectrums form
2.6 Variants
In many cases, if different scenarios are to be calculated with the same data basis, the variant switches for noise levels offered by this program can be sufficient. The definition of a spectrum contains 3 switches, which are related to the order of the project variants 1 to 3. Each variant contains a title which is to be entered into the parameter form. These titles will be used to generate titles in reports and graphics.
Two samples for using this instrument shall be described in the following paragraph:
According to the requirements of TA Lärm the variant 1 shall be the "day level", variant 2 the "night level" and variant 3 the "peak night level". The following level settings can describe these scenarios:
The source supply traffic is turned off at night. For a gate which is only shut at night, the attenuation is turned off at daytime. For a rarely reacting valve the power level is turned on only to determine the peak level. In the course of a plant redevelopment, variant 1 shall be the "Current state" and variant 2 shall be the "State of redevelopment". Obviously all new sources have to be turned off in the "Current state", in the "State of redevelopment" all removed sources have to be turned off, due to reconstruction.
A complete calculation course with appropriate calculation time and a report will be carried out for each variant.
3. Spectrums catalog and Generators
The "spectrums generators" encompass programs to generate noise spectrums for elements (e.g. steam throughput and temperature for a steam outlet) or the calculation of the emission level (Lm,E) according to RLS-90 and SCHALL 03 as well as access to lists for sound power, insulating materials or interior level of noise sources.
The spectrums generators can be accessed from the spectrums list or from the spectrums catalog by using the button in the tool bar or by right-clicking the mouse. Then the prepared spectrum can be transferred from the spectrums generator to the appropriate line in the spectrums list by clicking "OK"
The spectrums are calculated in the octave band accompanied by a weighted level.
3.1 Catalog manager
Independent from the project data, the catalogs can be stored in a separate folder and accessed from there.
The catalog tables are stored in files, which can be accessed via the catalog manager with the functions "Open", "New" and "Save as".
3.2 Catalog tables
For the classes POWER, ATTENUATION, INTERIOR (and others) catalog tables can be created. The tables offer an octave spectrum and a weighted level in each line. By clicking "OK" the spectrum of the current line will be transferred to the spectrums list of the current project. If this action is not desired, the tables has to be closed by clicking "CANCEL". The spectrums name and the category in the catalog will be transferred, too. These tables can be also created outside the program, in which case they have to be configured as described in Import/Export.
3.3 Calculation forms
The program offers forms for some simple sound-technical calculations, which calculate one octave spectrum (with the midband frequencies: 63, 125, 250, 500, 1000, 2000, 4000 and 8000 Hz) and one weighted level at a time. These data can be transferred to the spectrums list of the current project or a spectrums catalog:
Under the menu "Average sound level":
The form Average sound level for calculation of a average level for non-continuous noises. The assessment level according to TA Lärm is a mean level for the periods "loudest hour at night" on the one hand and for "16 day hours" on the other hand.
Under the menu "Sound power levels":
The functions RLS-90 and SCHALL 03 described below as well as the submenu "Installations" to determine the sound power from technical data of some components:The muzzle noise of gases diverting from a Stack, depending on flow rate, muzzle surface and temperature.
Noises which emit from a Fan to a duct system or to the ambient air, dependent on the type of fan, the air volume and the pressure difference.
The noises of an Electric motor dependent on the revolutions and the engine power.
The exhaust noises of a Steam pressure valve dependent on the steam throughput and the steam temperature.
Under the menu INSIDE ROOM:
The Interior level from the interior volume, the reverberation time and the entire sound power in the room.
3.4 Relative spectrum
Usually, there is no spectrum available in the calculation formula for sound levels. On the other hand, it can be necessary that the prognosis for sound levels is carried out in the octave spectrum. Between these two prevailing conditions the relative spectrum shall be a link, which is offered in every form. The frequency response of the noise, if known, is to be entered here by the user. The program will calculate an octave spectrum, which is derived from the weighted level received from the formula and derived from the relative frequency response.
If a spectrums form is exited by clicking "OK", this spectrum will be transferred to the current spectrums list. If this is not desired, the form has to be closed via "CANCEL".
3.5 RLS-90 and Schall 03
The forms RLS-90 (the guideline for protection against noise on streets, August 1990) and
With the block of primary input data (the first 6 entry fields), the calculation parameters (the following 6-8 entry fields) are calculated and from there the A-weighted emission level, as well as an octave band of the emission level with respect to the relative spectrum (chapter 3.4), are calculated.
The calculation parameters can be overwritten in the dialog, in which case the emission level will be calculated again.
The guideline RLS-90 states that the two directions are to be considered as independent sources 0.5 m above the road axis. In case of multiple-lane streets, the sources have to be placed in the center of the outer-most lane.
SCHALL 03 requires a source for each rail, each type of vehicle, each class with the same disk brake index and for each speed class.
The guideline SCHALL 03 offers 2 values for speed and length of different train types in the table:
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4. Analysis
The calculation steps to control and analyze the results can be made clear by the function "Analysis". These calculations are carried out independent from the prognosis and do not affect the results generated there.
Line sources (traffic sources) dependent on the receptor point distance will automatically be divided into sections, of which the length does not exceed half of the receptor point distance (RLS-90, 4.4.2). The emission of a so-called source element is placed in the center of a section.
In the following descriptions the name source, in case of line sources, refers to a source element. In the guidelines RLS-90 and SCHALL 03, the ground reflection is integrated and can not be considered as an additional image source.
The analysis calculations are only possible for a limited selection of sources (elements) and/or receptor points. Examinations of the calculation course in detail are possible with limitation to one receptor point and one source. The report contains all the details of the calculation course, which allow the verification of the calculation by hand. For the source and every reflection (ground reflections and obstacle reflections) the screening attenuation of the 3 considered sound paths (one way over and two ways around), the solid angle index (Ko) as well as all sound reducing values are listed.
When limiting one of the two lists (receptor points and sources) a result table will be generated through the non-limited parameter, which can, dependent on the switch setting "D-value-table" in the parameter form, appear in two different layouts.
see Analysis form
- In the attenuation value table, the elements of the propagation calculation for the source (or sources) and all related reflections are listed.
These are for point sources (calculation according to ISO 9613-2 (VDI 2714)):
| Nr | Name of the source or the receptor point, according to the choice of the list |
| Hi | Number of obstacles, which reflex is to be considered For realistic sources the Hi is left out, the ground has the obstacle number 0 |
| Lw | Sound power of the source |
| Dref | Reflection loss of the reflection sources |
| Ko | Solid angle index |
| sm | Linking path between source and receptor point |
| Ds | Distance |
| Dlg | Reduction for long term averaging |
| Dl | Absorption of sound by the atmosphere |
| De-Ü | Insertion attenuation of the way over |
| De-K | Insertion attenuation of the short way around |
| De-L | Insertion attenuation of the alternative way around |
| De | Insertion attenuation of the screens |
| Ddg | Vegetation/Development attenuation |
| Dbm | Ground/Meteorology attenuation |
| Ls | Sound pressure level on the receptor point |
These are for traffic sources (calculation according to RLS-90 or SCHALL 03):
| Nr | Name of the source or the receptor point, according to the choice of the list |
| Qele | Number of the source element |
| Hi | Number of obstacles, which reflex is to be considered. For realistic sources the Hi is left out, the ground has the obstacle number 0 |
| Lme | Emission level of the section |
| Dref | Reflection loss of the reflection sources |
| Di | Directivity index of rail sources |
| sm | Linking path between source and receptor point |
| Ds | Distance |
| Dlg | Linking path between source and receptor point |
| Dl | Absorption of sound by the atmosphere |
| Dr2 | Supplement for multiple reflections |
| Dt | Section supplement for line sources |
| De | Insertion attenuation of the screens |
| Ddg | Vegetation/Development attenuation |
| Dbm | Ground/Meteorology attenuation |
| Ls | Sound pressure level on the receptor point |
The table requires calculation with either a weighted level or one level from a selected frequency of spectrum. According to the selection of the calculation method, the levels are displayed in units (dB) or in (dBA).
- The illustration of the total receiver spectrum is alternatively possible, but without the D-values.
The calculation results and relevant input data are stored in a file with the extension .IDD. This file can be viewed or printed with the report function.
see Output sample
4.1 Propagation calculation
The mathematical handling of the sound propagation for point sources (facade sources and outside sources) is described in the guideline ISO 9613-2 (VDI 2714) and for traffic sources in the guidelines RLS-90 and SCHALL 03:
Ls=Lw+Ko-Ds-Dl-Dbm-Ddg-De-Dlg ISO 9613-2 (VDI 2714)
Ls=LmE+Ko-Ds-Dl-Dbm-Ddg-De-Dlg+Dt+Drefl RLS-90
Ls=LmE+Di+Ko-Ds-Dl-Dbm-Ddg-De-Dlg+19.2+Dt-5+Dr2 SCHALL 03
| Ls | Sound pressure at the receiver |
| Lw | Sound power of the point sources |
| LmE | Emission level for traffic sources |
| Di | Directivity index |
| Ko | Solid angle index |
| Ds | Distance |
| Dl | Absorption of sound by the atmosphere |
| Dbm | Vegetation/Development attenuation |
| Ddg | Ground/Meteorology attenuation |
| De | Insertion attenuation |
| Dlg | Reduction for varying winds |
| l | Length of a section element |
| Drefl, Dr2 | Supplement for multiple reflections |
| Dt | Section supplement for line sources (10*log(l)) |
Because P&K 2714 is using the guideline VDI 2710 Part 1 (Draft 1991) for the screening effect of buildings, it can do without the directivity index according to chapter 5.1 of the guideline ISO 9613-2 (VDI 2714). Only for rail sources is a directivity index considered:
Di = 10*log(0.22+1.27*sqr(sin(delta)))
The distance results to:
Ds = 10.9921+20*log(sm) ISO 9613-2 (VDI 2714)
Ds = -11.2+20*log(sm) RLS-90
Ds = 7.9818+20*log(sm) SCHALL 03
with sm as the distance between source and receptor point in meters. For reflection on the ground and on the obstacles, sm determines the location of the virtual image sources.
Deviating from the usually defined downwind average level, if a statement about the expected long term level (taking account of varying winds) is to be made, the reduction can be considered with sm as the distance from the source to the receiver (in m) (ISO 9613-2 (VDI 2714), page 9) (available in the parameter form).
Dlg = 3/((105/sqr(sm))+1.6)
Drefl and Dr2 are supplements for multiple reflection defined in the guidelines RLS-90 and SCHALL 03. This value is to be entered into the list of traffic sources manually. Both guidelines suggest for a gorge a value of 4*h/w with the gorge depth h and the width w.
For rail sources, the low disturbing effect of the railway traffic (SCHALL 03, Page 19) is considered by S=-5. All remaining parameters of this calculation are described in the following chapters.
4.2 Sound power of the Source (Lw)
According to requirements, the emission level for discrete noise sources will be displayed either A-weighted and/or in the frequency band.
For sound-absorbing facade elements, the sound power radiating to the outside is defined according to
Lw = Li-R'-9 calculation in the frequency band
Lw = Li-R'w-7 in A-weighted calculation with
| Li | Interior level |
| R' | Sound attenuation |
| R'w | weighted sound attenuation |
This does not consider a limit of the solid angle, because it is covered completely by the directivity index (Ko).
For reflection sources, the sound power will be reduced in accordance with the specified reflection losses for the ground and for each obstacle.
4.3 Solid angle index (Ko)
For the Solid angle index the relation Ko = -10*lg(O/(4*pi)) with O as the opening angle is set in the guideline ISO 9613-2 (VDI 2714), page 5, though it is implied that the restricted areas radiate the directed sound power completely.
P&K 2714 offers for the opening angle O a more differentiated statement, which considers the dispersion of the areas.
O = 4*pi-sum(10-Di/10*Ri) with Ri the solid angle index of the obstacle visible from the source i (for further explanations see 6.1)
Di: the relative reduction of sound power occurring because of dispersion loss on the obstacle i
A propagation loss of 3 dB describes the circumstance: that the radiated power reaches only 50 % of the directed power.
For traffic sources (RLS-90 and SCHALL 03) the solid angle index is not considered.
4.4 Absorption of sound by the atmosphere (Dl)
The absorption of sound by the atmosphere is described according to ISO 9613-2 or VDI 2714 (page 5) with Dl = alpha*sm. See Standards.
sm is the linking distance between sources and receptor point in meters. In the appendix C of
4.5 Ground/Meteorology attenuation (Dbm)
Ground and meteorology attenuation are considered in the guideline ISO 9613-2 (VDI 2714), chapter 6.3 with
Dbm = 4.8-2*hm*(17+300/sm)/sm.
Herein sm is the linking distance between source and receptor point, hm is the average height of this distance (both in meters).
In the context of the attenuation calculation, Dbm is considered as noise reducing. Therefore this value has to be also included as reduction of the attenuation (VDI 2720, chapter 3.2) for the calculation of the insertion attenuation for the sound path over the top of an obstacle (the reduction is not effective there anymore).
The mentioned formula for ground and meteorology attenuation, dependent on the frequency (appendix D of the guideline ISO 9613-2 (VDI 2714)) can not be used, because it includes the ground reflection and proceeds with the free sound propagation only. This program considers ground reflection explicitly and the influence of obstacles.
4.6 Vegetation/Development attenuation (Ddg)
As long as vegetation and development are not described by discrete objects, a consideration in form of a homogeneous noise absorbing layer up to a fixed height is possible. The sections of a sound path above this layer experience no attenuation. For the paths within the vegetation/development zone an attenuation value of
Ddg = k*sd*f1/3 with
| k | Coefficient (ISO 9613-2 (VDI 2714) as 0.006) |
| f | Frequency in Hz |
| sd | Path within the vegetation and development layer in m |
is considered.
The layer height and the coefficient k are definable through the dialog. The path sd will be derived from the sound path. In the context of the propagation calculation the sound path is the direct connection between source and the receiver (attenuation without obstacle).
If the sound path is diverted through obstacles, sd' is to be defined for this modified path. The resulting attenuation is to be named Ddg' (with obstacle). Since Ddg is considered in the propagation calculation, it has to be compensated to determine the insertion attenuation (VDI 2720, chapter 3.2).
4.7 Insertion attenuation (De)
The insertion attenuation of an obstacle within or nearby the connection distance between source and receptor point will be calculated by energetically subtracting all relevant sound paths (VDI 2720, chapter 3.1).
In
The shortest way (over) from the source over one or more obstacles projected onto the ground plane
The shortest way around the most left prominent edge of the obstacle nearest to the source perpendicular to the plane specified by way over the obstacle, the source pathlength difference
and the receiver.
The shortest right way around equivalent to the left way around.
The difference between the left and the right path applies just to the obstacle nearest to the source. For the further path to the receptor point, the shortest path around the possibly following obstacles (independent of right or left orientation) will be chosen.
An insertion attenuation according to VDI 2729, chapter 3.2 to chapter 3.5 will be calculated for these 3 sound paths:
De = Dz-Dbm-Ddg+Ddg' for the way over and
De = Dz-Ddg+Ddg' for the way around.
The chapter 3.6 describes the vegetation/development attenuation without (Ddg) and with (Ddg') obstacle, and the chapter 3.5 of this manual describes the ground/meteorology attenuation.
For Dz:
Dz = 10*lg(C1+C2/lam*C3*z*Kw) with
| C1 | 3 |
| C2 | 20 for the ways around |
| 40 for the way over | |
| C3 | (1+(5*lam/e)2)/(1/3+(5*lam/e)2) |
| Kw | exp(-1/2000*(aq*aa*sm/(2*z))0.5) for the way over = 1 for the way around or if z<=0 |
| lam | Sound wave length with a sound speed of 338 m/s (dry air of 10 °C and normal pressure) |
is valid.
From the geometries of way around and way over the following characteristics:
| e | Distance between the point of the way around or the way over next to the source and next to the receptor point |
| aq | Distance between source and the point of the way around or the way over next to the source |
| aa | Distance between receptor point and point next to the receptor point of the way around or way over |
will be derived to determine the pathlength difference z = aq+e+aa-sm. The pathlength difference is negative in case of a sight connection between source and receptor point, but it still can be a positive screening attenuation in case of small values (diffraction effect).
5. Noise prognosis
In the context of the prognosis, a complete calculation will be carried out for the specified application found in the menu under Edit. The result will be written into the result file in the form of a table with the frequency spectrums of the total levels on all receptor points. This result file is the data entry for the graphic illustrations of the prognosis results.
Before starting a time consuming calculation, the inputs can be checked for plausibility with the function "Test parameters". Invalid inputs will be commented on in the report after the checking. In the report trailer, hints for improperly overlapping obstacles or sources on the inside of obstacles can be found. Another meaningful control is the area map, already available at this time.
The prognosis result and the relevant input data are stored as a file with the extension .IDR. It also can be printed or viewed with the report function.
The report file of the prognosis has the following structure:
1. Protocol of input data with:
- Global parameter
- List of spectrums
- List of outside sources
- List of facade sources
- List of line sources
- List of obstacles
- List of receptor points
2. Error messages of the data verification
3. For each variant:
- List of the dominant sources on each receptor point. If calculated with octave spectrums, this is the source with the highest peak in the spectrum.
- List of levels on each receptor point.
see Report sample
6. Propagation Path
The program offers graphic illustrations to document details of a sound propagation calculation. Apart from the screening attenuation, necessary for the calculation of the propagation paths the building outlines are illustrated
This diagram requires the restriction of the view to one source, in case of line sources to a line segment and for the propagation paths to one receiver.
Into the calculation of Ko, only up to 10 of the objects with the largest solid angle and a corner in a radius of 100m around the source are taken into account.
The diagram shows the outlines of all buildings and the relevant propagation paths for the real source and all considered reflections. The descriptor can be added to the obstacles. At the location of the selected receiver / receptor point, the receiver number is shown and at the location of the source, the number of the source with the initial (A for outside, F for facade and L for line sources. For line sources, the position of the source segments are marked with a cross.
Ground reflections are considered only if the point of reflex is situated in a square with the edge length 100 m around the source. The ways of reflection are drawn starting from the place of the reflex.
For the paths around, both the short and the long way around the obstacles are represented . In case of free line of sight connection, only the path passing the closest diffraction edge is shown (not the direct connection).
In the case of sound diffraction around obstacles, also the propagation path over the objects is to be considered. The illustration shows the path over the obstacles.
7. Result graphics
The prognosis results as well as the geometric order for sources, receptor points and obstacles can be illustrated on the screen or can be printed.
The columns of the result table are optionally displayed :
- by colored shapes
- by placed numbers
- in form of Isolines
Scope and layout of the graphic illustration can be controlled by different forms in the menu under "Options" and "Axis".
7.1 Scaling
By setting intervals for X or Y-direction, a section can be chosen from the calculated receptor point area. From the inputs, the program determines an appropriate illustration. In addition the illustration can be zoomed or moved.
This function can be used for the area map and for the illustration of the results.
For further options see Axis settings
7.2 Legend
For the illustration of color shapes and Isolines, inputs are expected for the threshold values. From the threshold range and the number of thresholds, appropriate equidistant threshold values will be calculated in the form. This can be overwritten. If no minimum or maximum values have been chosen, the grade will be calculated automatically.
7.3 Object illustration settings
Symbols, numbers and colors of the geometric elements can be activated in the graphic output of the results and the area map:
- Circles for outside sources and facade sources
- Lines for traffic sources
- Crosses for receptor points
- Rectangles for obstacles
7.4 Illustration of numbers
A column of the result table will be shown on the screen in the form of placed numerical information. For a large number of receptor points, this is legible in a reduced section of the area only. The appearance of the numbers can be controlled in the form Settings of the ordinates
7.5 Illustration of colored shape
Around each receptor point, a quadratic colored area will be drawn, which represents the result value on the receptor point.
The value, which is related to each color in the legend, describes the lower limit for the corresponding value interval. The value corresponding to the following color describes the upper limit of the interval.
7.6 Illustration of the Isolines
One column of the result table is shown in the form of contour lines on the screen. The number value corresponding to the line color is listed in the legend.
The contour line generation selects between two methods automatically, depending on the receptor point area:
- In an area in which the receptor points are arranged in a regular quadratic net, a simple and fast method will be selected.
- Otherwise, the time requirement for creating the Isolines increases quadratically by the number of receptor points. With fast PCs the limit of what is reasonable is reached at 1000 receptor points.