Sound Intensity Manual

SOUND INTENSITY
InstallATion Guide

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Equipment required for the installation

Software CD containing OROS Sound Intensity.

One OROS Sound Intensity dongle and NVGate installed and authorized.

Installation

Installation of the NVGate software

-->In a first step, if it was not done before, NVGate Software should be installed:

To achieve this installation, please refer to the relevant installation guide delivered with your analyzer.

OROS Sound Intensity installation

-->In a second step, the OROS SOUND INTENSITY software can be installed:

1. Run the "setup.exe" file from the "software" directory of your installation CD.

2. Run the protection dongle driver installation by starting the "hldrv32.exe" file from the

"Hardlock Driver" directory of your installation CD.

3. Install the Acrobat Reader application from the "Acrobat reader" directory if it is not done yet.

4. Insert the USB dongle on the USB Port of your PC.

You are now ready to use the Sound Intensity Solution software.

The Online Help will give you further detailed information on the software use.

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SOUND INTENSITY User's manual

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Measuring Sound Power using Sound Intensity:
The basics

The sound power radiated by a noise source equals the sum of the scalar products of the sound intensity vectors by the elementary area vectors over a surface enclosing the sound source.

The OROS Sound Intensity package has 2 main objectives:

1. Calculate the sound power of a source from intensity measurements;

2. Allow a 3D representation of the sound emission distribution on the measurement grid.

The procedure followed by the software complies with the prescriptions of the International Standard ISO 9614. Such a tool is particularly helpful when one of the field indicators specified in the standard does not satisfy the necessary requirements. As a matter of fact, in some cases, the measurements must be repeated by successive refinements of the measurement grid. It's plain that this procedure could be rather time consuming.

The standard requires the definition of a measurement surface which encloses completely the noise source under test. Typically, the measurement area is a parallelepiped composed of five faces. Each of these faces is decomposed into discrete areas where measurement points will be positioned.

Typical Sound Intensity measurement

Each of these areas is called measurement segment or segment. In ISO 9614 Part I, each segment is associated with a measurement position whereas ISO 9614 Part II prescribes to scan the faces. The data stored during the measurement are the pressure and sound intensity levels in 1/1 or 1/3 octave bands.

According to the standard requirements the following information are also necessary have to be entered by the operator or calculated by the software:

• Description of the test source (Dimensions, etc. …)
• Description of the test environment (Air temperature, Static pressure, etc. …)
• Place and date of the measurements
• Expected grade of accuracy
• Test Equipment (Sound Intensity Probe type and S/N, Microphone pair etc …)
• Calibration set-up and procedure
• Pressure Residual Intensity index (also known as PRI Index)
• Geometric parameters of the measurement surfaces and segments

During the measurement, the sound pressure spectrum and sound intensity spectrum have to be monitored and are usually displayed in real time (1/1 or 1/3 octave spectra or even narrow band FFT spectra). The real time performances of the OROS PC Pack enable the program to show and import directly any pressure and intensity data from the analyzer, allowing thus a real time control of the measurement. It is possible to set up the acquisition procedure (measurement sequence or random access to the data structure) to decide in which way to fill up the segments or how to complete the measurements. A three dimensional visualization both of pressure and intensity fields on the measurement surfaces is displayed using color contour plots.

The calculation of the indexes defined by the standard giving information about the quality of the determination and hence its grade of accuracy is calculated repeatedly:

• Temporal variability indicator
• Pressure - Intensity indicator
• Negative partial power indicator
• Non uniformity indicator

If one of the indexes does not meet the requirements, the test procedure should be modified.

The Sound Power Level is calculated for each surface and each frequency complying with the ISO 9614-1 flowchart showing directly the needful steps the user has to undertake to comply with the Standard requirements. A table gives a comprehensive insight of the field indicators computed for each surface taken into account in the sound power computation. The acquisition and calculation procedures include the treatment of one-octave and one-third-octave band data as well as FFT data. The Sound Power levels are calculated for each surface and can be displayed also for the overall measurement surface with or without "A" weighting. Finally the following parameters are displayed:

• Sound power level spectrum
• Sound Power Report

Operating Modes

The software is organized around two main modes that correspond to two steps of the measurement procedure:

• Measurement surface and environment design using the Surface Editor Mode
• Measurement set-up, data acquisition and analysis using the Main Mode

The following figure shows the main user interface during the Main mode:

Main operation mode screenshot

These 2 modes have different objectives and consequently different functionalities will be active according to the active mode. One mode or the other is selected by pressing the corresponding icon in the task bar.

Wizard

The wizard is the fastest way to start with a new model. To start the wizard, select the wizard command from the file menu. The windows shown in the following figure will start guiding you through the next steps.

Start of the wizard

Clicking the Next button, the software will display the subsequently window, concerning the Project Name, the Creation Date, the User Name, the Project Description and the Comments.

Information section of the Wizard

The next step is to enter the environmental data, such as Temperature, Static Pressure and Relative Humidity.

Environmental data

Then the user has to choose the type of project (2D or 3D), the dimensions of the control surface enveloping the sound source and the number of segments for each dimension.

Geometry of the control surface.

The 5^th section concerns with the selection of the analysis parameters. The user has to choose the Standard to use for the determination, the Grade of Accuracy, the Averaging Mode and the Averaging Time.

Set up of the analysis parameters.

In the next window, the user has to select the spacers used to cover the frequency span of interest.

Spacer selection.

Select from the available spacers list the spacers you want to use during the measurement. Drag and drop the selected spacer on the desired row. To change the frequency range, click with the left mouse button on the frequency cell related to the desired spacer. The relevant frequency span lights up in green. To change the frequencies, the user has to click with the left mouse button on the lower or the highest frequency of interest while pushing the ctrl button on the desired minimum and maximum cells. You can activate each spacer by clicking on its name. The software rejects intersected frequency spans. You can also use multi-spacer mode selecting only one spacer to limit the overall frequency usage. Finally click on the Next button to reach the end of the wizard.

End of the wizard procedure.

Then the measurement surface will be displayed and the user will be able to start the sound power determination according to the Set-up edited in the previous sections.

Begin of the determination after the Wizard Setup.

It is also possible to start with the short Wizard by pressing the "New Project" button in the Main Menu: it offers to the users to input the main project properties:
	Create a new project

Surface Editor Mode

The first thing to do when starting a new project is to define the geometry of the measurement surface and the structure of the contained objects. In the Surface editor mode, the screen changes as shown:

Graphic editor mode

It's noteworthy the presence of a reference plane (dotted plane) functional to the generation of the surfaces. In fact each operation starts placing the first point of the object on this building plane.

Notice that there are two kinds of editable objects in this operation mode:

• Frames
• Surfaces

Frames are parallepipedic elements used to represent the source and its environment Surfaces are parallepipedic elements used to represent the measurement surfaces. They can be divided into segments, each one defining a measurement position. Measurement data can only be acquired or saved on a surface and not on a frame. Objects (Surfaces or Frames) are composed of one or several faces decomposed into segments. The above displayed figure shows the surface editor interface. In addition, the user can modify created object. In particular objects faces can be translated horizontally or vertically.

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D display tools

The 3D display tools described in this section are available when the corresponding option was purchased.

Using the mouse left button and specific keyboard keys (Ctrl and Alt) the 3D displays can be handled for:

• Translating the display origin: Drag with left mouse click. The Origin translation icon must be toggled on (for further details see Section 2).
• Rotate the display: Ctrl key + Drag with left mouse click
• Zoom the display: Alt key + Drag with left mouse click

Base Plane

While carrying out all the editing operations the snap function can be used in order to make the cursor move stepwise on the base plane.

All the editing commands are referred to the Base Plane that is the dotted surface on which the cursor can move.

The length of the step and the base plane extension can be set up by activating the button "Edit base plane dimensions" and dragging the bars to reach the required extension and the distance between two consecutive points.

The window and the relevant commands are shown in the following figure.

Graphic editor mode and Aids toolbar

Adding Objects & Faces (Surface or Frames)

To build a new frame or measurement surface, select the corresponding object on the tool bar shown in the right part of the screen when you are in the graphic editor mode and click with the left mouse button on the point you want to start from. Then drag the cursor on the dotted plane until you have reached the length required for the first side. Click left again and drag the cursor to build the base rectangle. At this stage you can "extrude" the third dimension and finish to build the surface by clicking the left mouse button in the place you want to put the third point.

Surface generation

Element Selection

In the Surface Editor mode several objects modification can be achieved if the element is previously selected. The element can be selected by using the selection icons placed on the task bar. Selection can be made on a segment, a face on an entire object or even several objects (It is always possible to select more than one object at a time). To unselect the selected element, one additional click on it or the use of the "unselect" icon will do the job. Selected elements are highlighted with a specific color.

Main tool bar

Element type Filtering

Before performing any modifications to the geometry, the user must decide if the actions have to be undertaken over frames or over measurement surfaces. To do this he has to select the object type using the appropriate command under the Edit / Selection Menu.

Element Translation

In order to be able to make geometric modifications (horizontal and vertical translation) an element (object or face) to perform the operation on should be selected (as described in section 3.4).

The Snap to grid function can be used to help objects be translated stepwise.

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Translation

With this command it is possible to move a selected element (object or face) in the graphic editor interface by keeping it parallel to the base plane. In this case, click with the left mouse button and drag the cursor in the desired direction.

Horizontal translation

Perpendicular Translation

This command is useful for moving the selected plane orthogonally to the dotted reference plane. You have to click the left mouse button also in this case and drag the cursor in the desired direction. Click the right mouse button or press the Esc button to quit the command.

Vertical translation

Project Manager

The Project Manager is always visible in the lower left part of the main window, as shown in the following figure. The tree structure shows the objects introduced in the projects by means of an icon. Each frame or surface can be decomposed in the single faces expanding the structure.

Project manager location

The user can see the properties of each item of the tree structure by selecting it and clicking with the right mouse button on the relevant icon. The properties change according to the item the user select from the project manager. Choosing "Properties" from the pop-up menu obtained for the whole surface, the user activates the window shown below:

Graphic properties window for a surface

The first column enables – disables the drawing of a surface, the edge column enables – disables the drawing of the edges of the surfaces, the Grid column enables to show the grid subdivision for the surfaces.

The Label column switches on – off the figures associated with each segment (pressure or intensity data).

Pressure values distribution over a measurement surface

The Name column enables to show – hide the name of each surface.

The Mfill column enables to show the filling sequence for each surface: it switches on – off the figures associated with the filling sequence adopted for a surface.

Filling order of a measurement surface

The black cell in the upper right angle is the starting point for the filling up which has to be set up with the project structure menu (see Project structure Section).

The last three columns are useful to set-up colors for the face and the grid of each face.

If the user selects the Surface Properties for a sub-surface, the program will open the following windows.

Properties window for a sub-surface

This window enables the user to set up and configure several surface properties:

Aspect Tab

• Number of horizontal and vertical subdivision of the surfaces;
• Drawing properties;
• Frame color;
• Overlay image (for 2D projects).

Overlay image.

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Measurement Tab

• Date and time of edition for the properties,
• Filling procedure.

The Surface Data command show a window containing Pressure and Intensity tabs, and enable the editing of the data loaded for the relevant surfaces.

Data can be exported in .txt files clicking on the relevant menu.

Project structure and Pressure tab

It is very important to distinguish the measurement surface from the frames. For this reason the measurements surfaces are described by coloured parallelepipeds and the frames by red gridded parallelepipeds.

Surfaces

Concerning the properties for the Surfaces, the user can set up:

• the number of subdivisions for each surface,
• the starting point to begin to fill the cells,
• The filling order.

In this way the user has to select, at first, the corner of the rectangle from which he begins to import and store the data.

The sort mode order can be chosen between two types:

• Z: the filling procedure goes on until it reaches the end of a row or a column, then it starts to fill the next row or column in the same direction of the first one.
• U: the filling procedure goes on until it reaches the end of a row or a column, then it starts to fill the next row or column in the opposite direction used for the first one.

The same window can be used also to select the surfaces for editing the geometry and to delete them. To select a surface the user has to double click on the frame or surface icon describing the item. The corresponding icon will light up. Then the user can enter the editing mode and choose if he wants to perform a geometry editing command (see the relevant section) or delete it. To delete the selected surface(s), click on the remove button.

The properties command activates a window. The first column enables to hide the frame corresponding to the selected cell. The second column hides the borders for the selected frame and the third activates/deactivates the grid. The name column enables to show the name linked to a surface. Finally the face and the grid columns can be used to change the color of these items for the selected frame.

Test Set-Up

The Analysis set-up is achieved with the Main Mode on.

Equipment Set-Up

In this window the user can choose the analyser Type and Model, select the microphone pair, the spacer length, and set up the remote control button functions.

Before starting a new real time acquisition session the user has to set up the analysis parameter. To do this, select the equipment group from the Set Up menu.

In the Analyzer tab the user can choose the Model of the analyzer used for the application. This task can be performed by clicking the relevant box and choosing the right item from the drop down menu. Another option is the selection of the NVGat.exe file. That can be done browsing the content of the Programs folder and selecting the relevant file.

In the Inputs tab it is possible to set up the channels coupling, the channel gain (the same for both channels), the probe gain (as info) and the polarisation voltage for the microphones (as info). In the case the user is employing an OR 3X analyser, it is possible also to select the physical channels attached to the intensity probe.

The Probe tab allows the user to select the probe type, the model, to enter the serial number, to set up the probe serial remote control and the keyboard shortcuts.

The Transducers tab enables the user to select the microphone pair by mean of a drop down menu linked to a transducer database. The value for the sensitivity will be loaded in the relevant fields of the table at the bottom of the window. All these values can be edited by clicking the table fields.

The table shown in the Spacer tab must be used to set-up the spacer length and the measurement frequency span for each one. The spacers defined in this tab are the only one visible and selectable during the editing and arrangement of the spacers in the Analysis Set-up.

The PRI index Tab shows the Pressure Residual Intensity Index for the measurement chain in use (both numerically and graphically) and the comparison with the IEC 61043 Standard Limits. Using the Load and Save buttons, the user can retrieve from or write to the disk several PRI profiles. Pushing the Set IEC 61043 PRI limits button, the default limits specified in the standard are loaded. The PRI here used is referred to the actual measurement chain and it follows the advices of the standards: the PRI is the one for the 25mm spacer. During the measurement the software automatically computes, depending on the spacer in use and its frequency range, the corrected values for each active frequency band. The values of the PRI spectrum can be edited typing in the Lp and Li cells (useful if the user has the probe/system calibration chart from the producer or the Calibration Laboratory).

In the Calibrators tab the user has to enter the data of the calibrators that can be used both for pressure and phase calibration (Manufacturer - model, Serial Number, Calibration level and frequency).

The user has to pay particular attention to the parameters edited in these fields because they can heavily affect the sound power determination.

Tabs for the equipment set-up

Analysis Set-Up

In the Analysis Set Up the user can enter and modify several settings referred to:

• The project data;
• The environmental settings;
• The FFT Analysis parameters;
• The spacers set up to cover the whole frequency span of interest;
• The grade of accuracy for the power determination.

Also in this case the user has to pay particular attention to the parameters edited in these fields because they can heavily affect the sound power determination.

Tabs for the analysis set-up properties

In the General tab the user can set up the project title and the user's name by entering the data in the relevant fields. To select the creation date click in the area and select the right one from the calendar.

The Environment tab can be used to enter the air temperature and the static pressure data. The air density will be computed according to the above entries. The user can also specify the information about the relative Humidity.

Through the Analysis tab the user can set up the averaging mode (linear or exponential) and the averaging time or the number of averages. The averaging time will be computed accordingly to the selected number of averages.

In the Spacers tab the user can select the spacers to use during the sound power determination and set up the frequency span for each one of them (and to cover the entire frequency span of interest).

If the user need to add a spacer or modify the list, he has to select the one he wants to use picking it from the Available spacers list (it is possible to modify this list only in the Equipment Set Up area).

The user has to Drag and drop the selected spacer on the desired row from the list.

Dragging and dropping the selected spacer in the desired row of the list placed in the upper part of the window, the user will be able to edit the frequency span covered by each one of them (modifying what is suggested in the table of the Equipment Set Up area).

To change the actual frequency range the user has to click the <ctrl> + "left mouse button" on the desired minimum or maximum frequency cell.

The software checks:

• if the spacers used are coherent with the actual spacer list set in the Equipment Set Up area
• if the higher frequency limit of the spacer if compatible (finite approximation criteria) with its physical length

and warns the user by both the coloured label and the message box confirmation closing this area.

Each spacer can be activated by clicking on its name. The relevant frequency span lights up in green. Please note that the software:

• doesn't accept intersected frequency ranges coming from more than one spacer
• requires that at least one spacer is selected
• warns if the range is not compatible

Please pay great attention about the PRI because Field indicators depend strictly on used spacers.

Summarizing the PRI usage:

• There is one Equipment PRI spectrum that refers to the measurement chain in the Equipment Set-Up area, and it represent the characteristic of the instrumentation used for the nominal spacer established by the standard at the 25mm length.
• There is the Active PRI spectrum used in the actual measurement and it is in the Analysis Set-Up area; it is affected by the spacer lengths finally used, dynamically computed upon the frequency bands associated to the spacer itself. Choosing different spacers combination with different frequency ranges, it is possible to see the effect directly in the following Accuracy and Ld. tab.

Control Panel

In the Accuracy and Ld tab the user can:

• set up the desired grade of accuracy among the types defined in the ISO 9614 Standard;
• find out or edit the pressure/residual intensity index stored for the apparatus;
• see the graph of the dynamic capability index of the selected measurement chain;
• Manually retrieve the values of the dynamic capability index from the file saved in the Analyzer set up configuration.
• It is also possible, pressing the lower button, to get (reset) the default PRI spectrum saved in the Equipment Set-Up Area.