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Contents
1 Introduction ............................................................................................................................. 1
2 Standards ................................................................................................................................. 1
3 Building Acoustics System Description ................................................................................. 2
3.1 Computer ........................................................................................................................................................ 2
3.2 Mezzo Unit ...................................................................................................................................................... 2
3.3 Microphone .................................................................................................................................................... 2
4 Step-by-Step Examples ........................................................................................................... 3
4.1 Start the Application ................................................................................................................................... 3
4.2 Configure the Microphone ....................................................................................................................... 4
4.2.1 Set the Microphone Sensitivity ................................................................................................ 4
4.3 Create a New Project ................................................................................................................................... 5
4.4 Add a Test ....................................................................................................................................................... 5
4.4.1 Performing an Airborne Sound Insulation Test .................................................................. 5
Measuring the Source Noise Level ...............................................................................................6
Measuring the Receiver Noise Level ............................................................................................9
Measuring the Background Noise Level ....................................................................................9
Measuring the Reverberation Time ............................................................................................9
Viewing the results........................................................................................................................ 12
4.4.2 Performing an Impact Sound Level Test ............................................................................. 13
Measuring the Receiving Level .................................................................................................. 13
Importing the Background Level and Reverberation Time ............................................... 14
Viewing the Results....................................................................................................................... 15
4.4.3 Performing a Reverberation Time Test ................................................................................ 16
Measuring the Reverberation Time ......................................................................................... 16
Viewing the Results....................................................................................................................... 17
4.4.4 Performing a Room Noise test ................................................................................................ 18
Measuring the Room Noise ........................................................................................................ 18
Viewing the Results....................................................................................................................... 19
4.4.5 Performing a Speech Privacy for Open Office Test ......................................................... 20
Measuring the Source Level ....................................................................................................... 21
Measuring the Receiver Level .................................................................................................... 22
Measuring the Background Level ............................................................................................. 23
Viewing the Results....................................................................................................................... 23
4.4.6 Performing a Speech Privacy Provided by a Closed Room Test ................................. 24
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Measuring the Source Level ....................................................................................................... 24
Measuring the Receiver Level .................................................................................................... 25
Measuring the Background Level ............................................................................................. 25
Viewing the Results....................................................................................................................... 25
5 Additional Information ......................................................................................................... 27
5.1 Noise Source Setup.................................................................................................................................... 27
5.1.1 Output Setup ................................................................................................................................ 27
5.2 Exporting Data ............................................................................................................................................ 27
5.3 Record Setup................................................................................................................................................ 28
1
1 Introduction
Congratulations on your purchase of the Mezzo Building Acoustics Module.
Intended to be used with the Mezzo Precision Microphone, the Mezzo Building Acoustics Module is
the perfect tool for the noise specialist providing an integrated project file with on-site reports:
• Airborne Sound Insulation,
• Impact Sound Level,
• Reverberation Time,
• Room Noise,
• Speech Privacy in Open Offices,
• Speech Privacy provided by a Closed Room.
The Mezzo Building Acoustics uses a project file approach combining measurements and test
reports in a single file.
This approach makes it easy to manage a large quantity of measurement and provide on-site
reports. The on-site reporting allows not only to view the test result instantly, but also to make sure
that no measurement was forgotten.
The current user guide describes the functionalities of the Building Acoustics Module. For more
information on the Mezzo Precision Microphone hardware, please refer to the Mezzo Precision
Microphone user guide.
2 Standards
Test Type Standards
Airborne Sound Insulation (ASI)
DW, DNW, DNTW, R’W (ISO 140-4:1998, ISO 717-1:2013)
NIC, NNIC, ASTC (ASTM E 0336:2005, ASTM E 0413:2004)
Impact Sound Level (ISL)
L’NW, L’NTW (ISO 140-7:1998 - ISO 717-2:2013)
FIIC (ASTM E 0989:2006, ASTM E 1007:2004)
Reverberation Time (RT)
T10, T15, Tdyn
T20, T30, EDT (ISO 3382-2:2008)
T25 (ASTM E 2235:2004)
Interrupted noise method
1/1 Octave and 1/3 Octave
Room Noise (RN)
NC, RNC, RC MkII (ANSI S12.2:2008),
RC, NCB (ANSI S12.2:1995)
NR (ISO 1996:1971)
Speech Privacy in Open Offices AI, PI (ASTM E1130:2002)
Speech Privacy provided by a Closed Room FIIC (ASTM E 2638:2010)
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3 Building Acoustics System Description
The following sub-sections describe the three main components of the Building Acoustics system:
the computer, the Mezzo unit and the microphone.
3.1 Computer
The PC is at the heart of the monitoring station. Of course, this PC needs to have the Building
Acoustics module installed.
Computer Requirements
Item Minimum Requirements
Operating System Windows XP SP3, Windows Vista, Windows 7, Windows 8
CPU Dual-Core at1.2 GHz
Memory 2 GB RAM
Hard drive 300 MB free hard disk space
Port USB 2.0
Minimal Display resolution 800 x 600
3.2 Mezzo Unit
The Mezzo unit provides the interface for signal measurement. It is connected to the computer
using the standard mini-B USB cable (included). The input of the Mezzo Precision Microphone is a
SMB connector, which usually hosts a microphone.
3.3 Microphone
The Mezzo unit supports any IEPE compatible microphones. The following table give the
recommended microphones. Recommended microphones are BSWA type MPA221 (Class 1) and
BSWA type MPA225 (Class 2).
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4 Step-by-Step Examples
This section describes how to use the Building Acoustics module through an example project.
4.1 Start the Application
The Mezzo Building Acoustics Module is part the Mezzo Suite installer. The latest release can be
downloaded from the Soft dB website (http://www.softdb.com/software.php?mezzo). The installer
installs the module and all the necessary drivers.
The Mezzo Building Acoustics Module can be loaded from Windows Start MenuAll
ProgramsMezzoBuilding Acoustics.
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4.2 Configure the Microphone
Connect the Mezzo unit to the computer using the provided standard USB cable (type Mini-B). A
small window appears to indicate that the software is connecting to the Mezzo unit.
4.2.1 Set the Microphone Sensitivity
The sensitivity of the Mezzo unit must be set in the software. From the Setup tab of the main panel,
press the Input Setup button to open the Input Setup interface. Then, press the Load From Mezzo
button to update the microphone sensitivity from the factory calibrated value. It is also possible to
perform a new calibration by clicking on the “calibrate” button.
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4.3 Create a New Project
A Project File includes all the measurement and test reports from a measurement campaign. It’s
recommended to use a single project file for a measurement campaign.
To create a new project, click on the “New Project” button from the Project toolbar and enter a
project name.
4.4 Add a Test
The measurements are related to tests of a certain type. Available test types are:
• Airborne Sound Insulation (ASI),
• Impact Sound Level (ISL),
• Reverberation Time (RT),
• Room Noise (RN),
• Speech Privacy in Open Offices (AI),
• Speech Privacy provided by a Closed Room (SPC).
4.4.1 Performing an Airborne Sound Insulation Test
Click on the Add Test button from the Project toolbar. Enter the test name and select “Airborne
Sound Insulation” from the test type drop-down menu:
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Once the test is created, you can enter the standard, partition area and the receiving room volume:
Note that you can change these values afterwards.
Measuring the Source Noise Level
Click on the “Add Measure” button from the project toolbar. Select “Source Level” from the drop-
down menu and click on “New Measurement”.
This operation will launch the measurement interface:
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Place the noise source in the source room and turn it ON. When you are ready to perform a
measurement, click on the “Run” button or press the top button on the microphone wand.
When you are ready to stop the measurement, click on the Stop button or press the middle button
on the microphone wand.
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If you are satisfied with the result, click on the “OK” button or press the middle button on the
microphone wand.
Once accepted, the result will appear in the list in the measurements tab:
It’s recommended to perform several source noise measurements. The software will average them
automatically.
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Measuring the Receiver Noise Level
Leave the noise source ON in the receiving room and go in the receiving room. Click on “Add
Measure” from the Project Toolbar, select “Receiver Level” from the drop-down menu and click on
“New Measurement”. Perform the measurement in a similar way as for the source level.
It’s recommended to perform several receiver level measurements. The software will average them
automatically.
Measuring the Background Noise Level
Turn the noise source OFF in the source room and return in the receiving room. Click on “Add
Measure” from the Project Toolbar, select “Background Level” from the drop-down menu and click
on “New Measurement”. Perform the measurement in a similar way as for the receiver level.
It’s recommended to perform several background level measurements. The software will average
them automatically.
Measuring the Reverberation Time
Move the noise source in the receiving room. Click on “Add Measure” from the Project Toolbar,
select “Reverberation Time” from the drop-down menu and click on “New Measurement”.
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Click on the “RT-60 Setup” button to select how to perform the test and select the measurement
mode from the drop-down menu:
The manual mode uses two threshold levels to detect the Noise source ON and OFF states. The user
must manually turn off the noise source to create the interruption.
The automatic mode uses the audio output of the tablet PC to control the source. The decay time
indicates the time to leave the noise source ON and OFF and the number of decays indicates how
many decay curves will be averaged. For 5 decays at 3s decay time, the measurement duration will
be 30s long. This method is faster and more reliable than the manual mode.
For the purposes of this example, the automatic mode will be used.
Click on the loudspeaker button to adjust and test the sound source:
Click on the blue “Play” button to test the volume and adjust the volume accordingly.
Click on “OK” to go back to the measurement interface.
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Click on the “Run” button to start the measurement.
At the end of the measurement, click on the “OK” button to accept the measurement:
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Viewing the results
Once all the measurements are taken, the result will appear in the “Results” tab.
Note that should you want to view the data against other standards, just select a different standard
from the “standard” drop-down menu from the Info tab.
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4.4.2 Performing an Impact Sound Level Test
Click on the Add Test button from the Project toolbar. Enter the test name and select “Impact
Sound Level” from the test type drop-down menu:
Once the test is created, you can select the standard and enter the receiver room volume:
Note that you can change these values afterwards.
Measuring the Receiving Level
Click on the “Add Measure” button from the project toolbar. Select “Receiver Level” from the drop-
down menu and click on “New Measurement”.
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Position the Normalized Tapping Machine
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at the first position on the source room floor and turn it
ON.
Click on “Run” on the measurement interface and perform the measurement in a similar manner as
for the receiver level of the airborne sound insulation test performed previously.
Move the tapping machines for the other positions required by the standard and perform the
measurement(s).
Importing the Background Level and Reverberation Time
The receiver room being the same as for the airborne sound insulation test, we will use the same
background level and reverberation time measurements for this test to save time.
Click on the “Add Measure” button from the project toolbar and click on “Load From Current
Project”.
Select the measurements you wish to import and click on “Add Selection”. Once imported, the
measurements will appear in the list on the Measurements tab.
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The tapping machine must conform to specifications given in appendix A of ISO 140-7 (1998) standard.
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Viewing the Results
Once all the measurements are taken, the result will appear in the “Results” tab.
Should you want to view the data against other standards, just select a different standard from the
“standard” drop-down menu from the Info tab.
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4.4.3 Performing a Reverberation Time Test
Click on the Add Test button from the Project toolbar. Enter the test name and select
“Reverberation Time” from the test type drop-down menu:
Once the test is created, you can select the standard and select the spectrum type.
Note that you can change these settings afterwards.
Measuring the Reverberation Time
Since the room under test is the same as the receiving room for the Airborne Sound Insulation test,
we will simply import the reverberation time measurements which were already performed. For a
detailed process on how to measure the reverberation time, refer to section Measuring the
Reverberation Time, p. 9.
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Click on the “Add Measure” button from the project toolbar and click on “Import From Current
Project”. Select the appropriate measurements from the list and click on “Add Selection”.
Viewing the Results
Go to the “Results” tab to view the resulting Reverberation time for each octave band or fractional
octave band.
The “Dyn” column indicates the dynamic which is the difference between the source level and the
background level. The TX represents the RT-60 reverberation time in seconds and R² indicates the
correlation coefficient between the measured decay curve and the linear regression curve.
The following table shows the different available RT-60 metrics:
Tag Linear Regression Range Minimum Dynamic Range Standard
Tdyn -5 to --* 15 dB ---
EDT 0 to -10 dB 25 dB ISO 3382-2
T10 -5 to -15 dB 30 dB ---
T15 -5 to -20 dB 35 dB ---
T20 -5 to -25 dB 40 dB ISO 3382-2
T25 -5 to -30 dB 45 dB ASTM E 2235
T30 -5 to -35 dB 50 dB ISO 3382-2
* Tdyn uses all the available dynamic range to evaluate the decay curve.
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4.4.4 Performing a Room Noise test
Click on the Add Test button from the Project toolbar. Enter the test name and select “Room Noise”
from the test type drop-down menu:
Once the test is created, you can select the standard from the drop-down menu.
Note that you can change this setting afterwards.
Measuring the Room Noise
Since the room under test is the same as the receiving room for the Airborne Sound Insulation test,
we will simply import the background noise measurements which were already performed.
Click on the “Add Measure” button from the project toolbar and click on “Import From Current
Project”. Select the appropriate measurements from the list and click on “Add Selection”.
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Viewing the Results
Go to the “Results” tab to view the resulting Room Noise criteria.
Note that you can view the dataset against another standard curve by selecting another metric
from the “Standard” drop-down menu from the Info tab.
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4.4.5 Performing a Speech Privacy for Open Office Test
Click on the Add Test button from the Project toolbar. Enter the test name and select “Articulation
Index” from the test type drop-down menu:
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Measuring the Source Level
The sound source level must be previously measured in an anechoic room on the loudspeaker axis
at 0.6m, 0.9m and 1.2m from the source point. The volume settings must be noted and must be
able to be reproduced on the site in a reliable and precise way.
To record the source levels, install the sound source in an anechoic room and set the volume
correctly. Create an empty Project and add an Articulation Index test. Measure the source levels by
adding 3 measurements at respectively 0.6m, 0.9m and 1.2m from the sound source. This Project
will be used later to import these measurements.
Back to the field measurements, click on “Add Measure” and select “Load from Another Project”:
Browse to the previously created Project file containing the sound source calibration
measurements:
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Select the 3 source measurements and click on “Add Selection”.
Measuring the Receiver Level
Back to the field, position the sound source at the talker location at a 1.2 m height above the floor.
The source shall be oriented towards the listener location and at 25° above horizontal. Set the
volume at the same position as it was during the anechoic calibration.
Position the microphone at the listener location at 1.2m above the floor.
Click on “Add Measurement”, select “Receiver Level” from the drop-down menu and click “New
Measurement”.
Perform the measurement as described in section Measuring the Source Noise Level, p.6.
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Measuring the Background Level
Click on “Add Measurement”, select “Background Level” from the drop-down menu and click “New
Measurement”.
Perform the measurement as described in section Measuring the Source Noise Level, p.6.
Alternatively, the background level could be loaded from a previously made measurement if
applicable.
Viewing the Results
Go to the “Results” tab to view the resulting Articulation Index and Privacy Index values.
The following table lists the criteria against subjective ratings of speech privacy:
AI PI Subjective Rating
AI ≤ 0.05 PI ≥ 95 Confidential
0.05 < AI ≤ 0.2 95 > PI ≥ 80 Normal
0.2 < AI ≤ 0.3 80 > PI ≥ 70 Poor
0.3 < AI ≤ 0.4 70 > PI ≥ 60 Bad
0.4 < AI 60 > PI No Privacy
Should you want to evaluate the privacy level for another type of speech, simply select the
appropriate speech type from the “Speech” drop-down menu from the Info Tab.
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4.4.6 Performing a Speech Privacy Provided by a Closed Room Test
Click on the Add Test button from the Project toolbar. Enter the test name and select “Speech
Privacy Class” from the test type drop-down menu:
Measuring the Source Level
Position the sound source in the source room and turn it ON.
Click on “Add Measurement”, select “Source Level” from the drop-down menu and click “New
Measurement”.
Perform the measurement as described in section Measuring the Source Noise Level, p.6.
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Measuring the Receiver Level
With the source still ON in the source room, go to the receiving room and position the microphone
at the listener location.
Click on “Add Measurement”, select “Receiver Level” from the drop-down menu and click “New
Measurement”.
Perform the measurement as described in section Measuring the Source Noise Level, p.6.
Measuring the Background Level
Click on “Add Measurement”, select “Background Level” from the drop-down menu and click “New
Measurement”.
Perform the measurement as described in section Measuring the Source Noise Level, p.6.
Alternatively, the background level could be loaded from a previously made measurement if
applicable.
Viewing the Results
Go to the “Results” tab to view the resulting Speech Privacy Class value.
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The following table lists the Speech Privacy Class criteria against subjective ratings of speech
privacy:
SPC Subjective Rating
70 Minimal Privacy
75 Standard Privacy
80 Standard Security
85 High Security
90 Very High Security
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5 Additional Information
5.1 Noise Source Setup
It is possible to use the audio output of the tablet PC to feed the noise source not only for the RT-60
but also for the source and receiver levels. To use the audio output, click on the “Noise Source
Setup” button in the measurement interface and check “Use Audio Output”.
Using this option, the noise source will turn ON and OFF automatically when performing the
measurement.
5.1.1 Output Setup
The output setup allows to configure the audio output of the tablet PC to be used as a noise source
for the STC tests and RT-60 tests. The generator outputs a pink noise for both audio channels. Two
equalizers can be added to customize the sound on each channel. As an example, one channel can
be connected to an omni-directional speaker (dodecahedron) while the other can be used with a
low-frequency speaker. Hence, two different equalizers can be used for better performance.
5.2 Exporting Data
The data can be exported to a text file (tab delimited) for a single test or the complete project. Click
on the “Export Test” button to export a single test or “Export Project” to export all the tests from
the project.
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5.3 Record Setup
Click on the “Record Setup” button from the “Setup” tab to access the record parameters.
The automatic save mode will automatically create a project file in the record directory upon
creating a project and will automatically save the file every X minutes.
In manual mode, the user must manually save the project to a file.
The automatic mode is recommended to avoid losing any data.
