HBK 2255 User Manual
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HBK 2255 User Manual

Sound level meter
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HBK 2255
with Building Acoustics Partner
User Guide
for Version 1.3
BN 2497–15
Copyright © Hottinger Brüel & Kjær A/S. All rights reserved.
2024.0

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Summary of Contents for HBK 2255

  • Page 1 HBK 2255 with Building Acoustics Partner User Guide for Version 1.3 BN 2497–15 Copyright © Hottinger Brüel & Kjær A/S. All rights reserved. 2024.0...

  • Page 3: Table Of Contents

    Impulsive or interrupted method Number of positions Frequency range and measurement time Planned or unplanned measurements Smart Power Amplifier HBK 2755 All settings ADD ROOMS AND PARTITIONS Set up rooms and partitions in the application Typical source and receiving room layouts...
  • Page 4 Table of contents Reusing measurements Override the plan Example airborne sound insulation test Graphical displays Measurement overview Quality indicators Adapt to conditions REVIEW DATA At the end of a measurement Use the overview Open a measurement Expected results Find problems Remeasure IMPORT DATA TO THE PC APP Import a project...
  • Page 5 Import from Measurement Partner Suite ABOUT THE INSTRUMENT Hardware interface Instrument GUI Web server display Charge the battery Fix an unresponsive instrument Input settings TEDS, Microphones and HBK 2255 Microphone database Audio recording Display settings Regional settings Power management Data management Network settings...

  • Page 6: Types Of Tests

    TYPES OF TESTS Sound insulation tests The purpose of sound insulation measurements is to quantify how easily sound transfers between spaces in a building which are separated by building elements, such as walls, floors and windows. These separating elements are typically called partitions in the context of sound insulation tests.
  • Page 7 Types of tests Typical result parameters: Normalized impact sound pressure level = L – 10log(A/A is the impact sound pressure level, A is the absorption area in the receiving room, and A is the reference absorption area. Standardized impact sound pressure level = L –...

  • Page 8: Room Background Noise Tests

    Types of tests Field vs laboratory measurements Measurements in the field are performed in situ on partitions of buildings. The results are used to document con- formance to building regulations and design criteria. In field measurements, sound and vibration propagate not just via the partition under investigation, but also via other partitions, structures and leaks.

  • Page 9: Equipment And Accessories

    EQUIPMENT AND ACCESSORIES To perform sound insulation tests as described in this documentation, you will need HBK 2255 Sound Level Meter with Building Acoustics Partner and a sound source. The sound source can be HBK 2755 Smart Power Amplifier and OmniPower Sound Source Type 4292-L, or it can be a different sound source that fulfils the requirements of the stand- ard to which you are testing.

  • Page 10: Supported Standards

    SUPPORTED STANDARDS Building Acoustics Partner supports a wide variety of national standards as well as ISO standards, for both field and labor- atory use. You can only use one standard per project. The mobile app and the PC app include information about which version of the standard Building Acoustics Partner sup- ports.
  • Page 11 Supported standards DnT,A NEN'06 5077 5077 5077 NPR 5097 LnT,A 5077 5077 5077 5077 5077 5077 E413-73 ASTM E336-90 E966-90 E1007-11 E989 E1332-90...

  • Page 12: Download The Apps

    Microsoft Office 2016 or later Procedure: 1. Go to: www.bksv.com/downloads. 2. From the list of available downloads, expand the HBK 2255 section. 3. Select the software downloads option. 4. Scroll down to Building Acoustics Partner. 5. Once the download is complete, double-click the file (Setup.exe) to start installation.

  • Page 13: Connect Devices

    CONNECT DEVICES You will use both the mobile app and the PC app to work with Building Acoustics Partner projects. Projects are stored on the instrument, and you connect the apps to the instrument to work with the project. The mobile app and the PC app do not connect to each other.

  • Page 14: Connect The Pc App To The Instrument

    Connect devices Connect multiple instruments to the mobile app Building Acoustics Partner supports the use of multiple instruments. The ability to connect two instruments enables you to measure two positions simultaneously, which is a requirement for some façade sound insulation test methods. The process is similar to connecting one instrument, with the addition of setting the primary and secondary instruments.

  • Page 15: Create A Project

    CREATE A PROJECT A Building Acoustics Partner project stores the settings, measurements and results for sound insulation and/or room background noise tests. Projects are stored on the instrument. You can create a project, configure project settings and add rooms and partitions to the project using either the mobile app or the PC app.

  • Page 16: Configure Project Settings

    CONFIGURE PROJECT SETTINGS You can configure the settings for your sound insulation tests and room background noise tests using either the mobile app or the PC app. If you configure the settings on the PC app, you will need to upload the project definition to the instrument before you can open the project on the mobile app.
  • Page 17 Configure project settings Fixed measurement points ≥ 0.7 m (2.3 ft) between microphone positions ≥ 0.5 m (1.64 ft) from the room boundary ≥ 1 m (3.28 ft) from the loudspeaker Manually-scanned microphone traverse ✐ Note: The cylindrical scan requires Microphone Extension UA-0049. Low-frequency procedure The low-frequency procedure requires fixed microphone positions in a minimum of four corners, with two corners at ground level and two corners at ceiling level.

  • Page 18: Impulsive Or Interrupted Method

    Configure project settings Pros and cons of measurement methods Manually-scanned method Measurements at fixed points Scans can be faster than measuring at fixed pos- You can control measurements from outside the itions. Pros room, without introducing extra absorption or You are able to listen to the sound field as you noise inside the room.
  • Page 19 Configure project settings Example setup (impulsive noise) The following is an example of the settings used to make reverberation time measurements using impulsive noise. On the mobile app: Sound insulation setup > Measurement plan > Reverberation measurements On the PC app: Sound insulation setup > Reverberation measurements No.
  • Page 20 3. After the build-up time has passed, the instrument calculates the sound level generated. 4. The mobile app switches off HBK 2755 and tells the instrument to start the decay measurement. 5. The decay measurement stops automatically when the instrument detects the background noise level (or the elapsed time exceeds 30 s).

  • Page 21: Number Of Positions

    Configure project settings Number of positions The characteristics of the room (size, shape and furnishings) affect the reflection of sound within the room and change the sound field within the room, which can cause variations in sound pressure level within the room. For this reason, measurements are normally made at several points in each room.
  • Page 22 Configure project settings Example sound insulation test setups For planned measurements, the number of source and microphone positions for airborne, impact and façade sound insu- lation tests are set in the Sound insulation setup group of settings (in the Measurement plan group of settings in the mobile app).

  • Page 23: Frequency Range And Measurement Time

    Configure project settings Low-frequency procedure You can set the number of source and microphone positions for level measurements according to the low-frequency pro- cedure in the Level measurements group of settings. No. of LF receiving room pos. = 4 In the Airborne group: No. of LF source room pos. = 4 ✐...
  • Page 24 Configure project settings Measurement time (averaging time) In general, use an averaging time that gives a good representation of the average sound levels in the frequency range you are measuring. Higher frequencies require less averaging time than lower frequencies, so the lowest frequency band you choose to include in your measurements will normally determine the minimum appropriate averaging time.
  • Page 25 Configure project settings If you plan to measure at fixed positions, it is recommended to set up level measurements to stop automatically after a set length of time. Use the following settings: In the mobile app: Sound insulation setup > Measurement control L1 & L2 In the PC app: Setup >...

  • Page 26: Planned Or Unplanned Measurements

    Not applicable Hint: Predefined metadata on HBK 2255 makes it possible to use only the instrument to make sound insulation measurements. Manage metadata at the end of each measurement, then import your measurements to the mobile app or the PC app.
  • Page 27 Configure project settings Measurement assistant = Enabled The Measurement assistant setting enables or disables the mobile app to give you prompts and messages which help guide you through your tests. The assistant can be helpful if you do not have a lot of experience performing sound insulation tests.

  • Page 28: Smart Power Amplifier Hbk 2755

    If you are not using HBK 2755, do not worry. With Building Acoustics Partner, you can use any sound source which fulfils the requirements of the standard used, but you will set up and control the amplifier manually.
  • Page 29 Source type = Manual When using an amplifier that is not HBK 2755, the mobile app will wait for the sound level to exceed a preset trig- ger level before starting a measurement. Trigger levels are set in the Measurement control group of settings.

  • Page 30: All Settings

    You will not generally need power compression compensation when making reverberation time measurements as the sound source is not active for a long period of time. Example settings for reverberation time measurements using an amplifier that is not HBK 2755: Source type = Manual...
  • Page 31 Configure project settings Sets the frequency range on the graphical displays and for analysis. The setting is applied at the room/partition level, according to the type of test or tests to perform. A Building Acoustics Partner project can be set up to use different frequency ranges for sound insu- lation tests and room background noise tests.
  • Page 32 Configure project settings Measurement plan settings The Measurement plan group of settings allows you to customise the support the mobile app gives you during tests. A measurement plan establishes a step-by-step procedure that is applied to each test in your project. A measurement plan defines the number of measurements to make, the order in which to make measurements, the rules for reusing measurements and whether or not you want the mobile app to provide assistance.
  • Page 33 Sets the number of positions at which you will operate the sound source (or sound sources) in the source room. If you are using HBK 2755 to drive two loudspeakers simultaneously in two positions, set the number of source positions to one.
  • Page 34 Configure project settings Defines the order in which measurements are made, which ultimately determines how you will move equipment and yourself around the test site. Select Mic. position first to measure at each microphone position for the first sound source position, then measure at each microphone position for the second sound source position, and so on.
  • Page 35 Trigger level urement. A level between 80 and 100 dB is normally adequate. ✐ Note: If you are using HBK 2755, the Trigger level setting is not used. Defines how to measure L1 and L2 measurements. Select Simultaneously to make L1 and L2 measurements at the same time.
  • Page 36 Configure project settings Set the frequency band or bands to measure for serial measurements. The setting can only be Serial bands configured using the mobile app. Defines the excitation method you will use for reverberation time measurements in sound insu- lation tests and/or room acoustics tests.
  • Page 37 Tells the mobile app how the sound source will be controlled: manually or automatically. You can use any sound source which fulfils the requirements of the standard used, but HBK 2755 is the only sound source the mobile app can control automatically. See External devices for information about connecting HBK 2755 to the mobile app.
  • Page 38 White noise can be preferred in situations where increased output is needed at higher frequencies. HBK 2755 has special pink and white noise signals which contain more energy at higher fre- quencies. The special signals are used when the frequency range is set to include the 10 kHz fre- quency band.
  • Page 39 Configure project settings Allows you to lower (attenuate) the output of HBK 2755. In other words, the Output gain set- ting allows you to control how much noise HBK 2755 will make. To enable the setting: Source type = HBK 2755 You can enter values between –90 and 0 dB.
  • Page 40 Configure project settings Enables or disables a feature on HBK 2755 which stabilises loudspeaker output power. ✐ Note: Power compression compensation works by increasing the gain as the loudspeaker heats up to maintain a constant acoustical output during longer measurement times.
  • Page 41 L2 is made and quality indicators mark where corrections have been made. Quality indicators for more information about the indicators. If L2 – B2 < 6 dB and you are using HBK 2755 Smart Power Amplifier, you can set up the pro- ject to make measurement in serial. See Serial measurements for more information.
  • Page 42 PC and mobile device. Voltage output: Settings that allow you to output an input signal. External devices: Settings for using a weather station with HBK 2255. Advanced settings: Most of the advanced settings can only be accessed on the instrument. See Calibration set- tings...

  • Page 43: Add Rooms And Partitions

    ADD ROOMS AND PARTITIONS You can perform room background noise tests and sound insulation tests using Building Acoustics Partner, and both types of test can be included in a single Building Acoustics Partner project. A Building Acoustics Partner project can include room background noise tests for one or more rooms as well as sound insulation tests for one or more partitions.

  • Page 44: Typical Source And Receiving Room Layouts

    Add rooms and partitions Reuse measurements from: The room from which to reuse measurements. You can choose any room that has been added to the project or None if you do not want to specify a single room from which to reuse measurements. See Measurement reuse for more information.

  • Page 45: How To Choose Rooms And Partitions

    Add rooms and partitions Surface area of a partition The partition area is used in the calculation of results. Only calculate the area of the partition that is common to both the source room and the receiving room. How to choose rooms and partitions In general, when choosing source and receiving rooms, use the smaller of the two rooms as the receiving room.

  • Page 46: Low-Frequency Method

    Add rooms and partitions Low-frequency method It is very hard to get a good average of low-frequency levels in small rooms. For this reason, some standards (such as ISO 16283) include measurement procedures which are used to adjust low-frequency bands in sound insulation cal- culations.

  • Page 47: Measure

    MEASURE You can use the instrument or the mobile app to make a measurement. The mobile app makes it possible to start meas- urements remotely and its interface has a lot of functionality that is not on the instrument. However, if you are using a hand-held measurement method, it makes sense to start a measurement using the instrument.
  • Page 48 Measure For an unplanned measurement: Use the buttons to set the partition, type of measurement and position to match your equipment. In the example above, the mobile app is set to measure L2 for the first source position (S1) at the first microphone position (R1) for the partition between rooms 1 and 2.

  • Page 49: Reusing Measurements

    Measure Reusing measurements Reusing measurements affects the measurement process. Building Acoustics Partner allows you to set up measurement reuse so that it is automatic, manual or off. See Measurement reuse for more information. When reuse is automatic Measurements are listed and applied in the measurement overview. For planned measurements, the mobile app will skip measurements at positions where a measurement is reused.
  • Page 50 Measure Increment = Mic. position first In the Airborne group: No. of source positions = 2 Measurement control T2 > Excitation = Impulsive noise Procedure 1. Measure the background noise level in the receiving room (B2). 2. Measure the sound pressure level in the receiving room (L2) for the first source position (S1) at each microphone position (R1 to Rn).
  • Page 51 Measure 4. Measure the sound pressure level in the receiving room (L2) for the second source position (S2) at each micro- phone position (R1 to Rn). 5. Measure the sound pressure level in the source room (L1) for the second source position (S2) at each micro- phone position (R1 to Rn).
  • Page 52 Multiple instru- ments for more information. 2. If you are using HBK 2755 and you set an escape time, Building Acoustics Partner counts down the time to exit the room. 3. The sound source starts. 4. If you set a build-up time in the Source control L1 & L2 settings, Building Acoustics Partner waits for the time to pass.

  • Page 53: Graphical Displays

    Measure If you are using the interrupted noise method and HBK 2755, you can set escape and build-up times. Escape and build- up times work as they do in the level measurement cycles. Graphical displays Detailed measurement views in the mobile app allow you to understand exactly what is happening with your data.
  • Page 54 Measure Reverberation time measurements (T2) The profile graph helps you to visualise the reverberation time calculation. The graph shows either the raw time data without any manipulation on levels and time and without any markings, or the calculated regression line. Double tap the graph to switch between the views.
  • Page 55 Measure To add an exclude marker in the mobile app: 1. Tap and hold to set the first marker boundary. 2. Without lifting your finger, drag the cursor left or right to set the second boundary. 3. Lift your finger. Once you lift your finger, you will not be able to move the boundaries of the marker until after you add the marker.

  • Page 56: Measurement Overview

    Measure Measurement overview The Overview page in the mobile app gives you a test-level view of your data. The page helps you to keep track of meas- urements, to visualise the measurement data, and to evaluate the quality of each measurement. Use the page to make sure you have the data you need to complete your report before you leave the site.
  • Page 57 Measure The list of positions allows you to see quickly which measurements have been completed, and to include or exclude pos- itions from the room average. The room average is at the top of the list with the source/microphone positions nested below.

  • Page 58: Quality Indicators

    Measure The overview shows a profile display and a list below. The rating parameter is at the top of the list with all meas- urements for the partition nested below. Tap the profile to move the cursor. Tap the rating parameter to select a different parameter to view. Tap the plus/minus button to expand or contract the positions for each type of measurement.
  • Page 59 Measure The chosen result parameter cannot be calculated as the The partition area is undefined partition area has not been defined. Manual data input Data entered by user (level, reverberation time) Affected by manual input Data entered by user (level, reverberation time) No B2 measurements No B2 measurements available Background noise correction used...

  • Page 60: Adapt To Conditions

    Measure T20 used (T30 unavailable) T20 used (T30 unavailable) Receiving room volume limited Used on the SS standard only Try other source or microphone positions, or increase the L1: >6 dB difference to adjacent band amplitude of the generator signal at the affected fre- L1: >8 dB difference to adjacent band quencies The standard deviation in a frequency band is greater than...
  • Page 61 Measure Remeasure Building Acoustics Partner helps you respond to problems that may arise, such as unexpected noises during meas- urements or measurements in the wrong position. The opportunity to review measurements and quality indicators helps you to determine immediately if you need to remeasure. The ability to reject, remeasure and move measurements gives you options to find the best method to correct a problem.

  • Page 62: Review Data

    REVIEW DATA The mobile app gives you plenty of opportunities to review your measurement data. Detailed measurement views and quality indicators allow you to understand what is happening with your data before you leave the building site. At the end of a measurement At the end of each measurement, you have the opportunity to review the measurement.

  • Page 63: Expected Results

    The measured spectrum of level measurements in the source room (L1) should have characteristics similar to the output of the sound source, that is pink or white noise. If not, check your sound source and perform a calibration check on the instrument (HBK 2255). Are the levels matching your expectations? Receiving room levels (L2) should be above the background noise levels (B2) and below the source room levels (L1).

  • Page 64: Remeasure

    Review data Checks In the Calculations settings, there are some settings you can enable which will check for common problems. L1: Check dB rule: Enables the app to check that the level differences between adjacent third-octave bands are within the tolerance defined by the standard you are using. L1, L2: Check std.
  • Page 65 Review data Review the measurement At the end of each measurement, you have the opportunity to review the measurement. Use the opportunity to check the graphical displays of measurement data and check any quality indicators that were applied to the measurement. After you review the measurement, you will be prompted to accept or reject the measurement.

  • Page 66: Import Data To The Pc App

    IMPORT DATA TO THE PC APP Import a project to the PC app to analyse measurement data, to generate reports, or to export raw data for use in another application (such as Microsoft® Excel®). Import a project To import projects from to the PC app, you will need to connect the PC app to the instrument. You do not need to be connected to the instrument to create a project or to work with a project that has been imported and saved to a loc- ation on your PC or network.

  • Page 67: Measurement Icons

    You can share a project from the mobile app or the PC app. The sharing feature uploads the project to the HBK cloud and generates a download link which you share by email or message (when sharing via the mobile app).

  • Page 68: Analyse Data

    ANALYSE DATA Upon import to the PC application, all measurement data is available in graphical and tabular formats. Basic controls and general information Left panel The panel on the left includes a project browser and a task monitor. Select an item in the project browser to view data, settings, options and annotations for that item.
  • Page 69 Analyse data Centre window The main window provides context-sensitive views of the project. Depending on what is selected in the project browser, you can view setup information, the graphical and tabular displays of measurement data and report previews. Select the Measurements tab to view the measurement data. The vertical tabs on the left side of the window open the different views for reverberation time measurements, level measurements, results and a list of measurements.
  • Page 70 Analyse data Tables Select a measurement type to view its graphical display. Double-click a header to sort the table. Use the context-sensitive menu to access options to copy the table data (in CSV format), to revert overwritten data, and to delete, cut or paste positions. Double-click a cell to overwrite the data.

  • Page 71: Project Browser

    Analyse data Project browser The project browser gives an overview your Building Acoustics Partner project and allows you to select items to view. The project browser organises projects by rooms, partitions and background noise (rooms). Basic controls and functionality The project browser controls what is displayed in the application. Select an item in the project browser to view the data, settings, options and annotations for that item.
  • Page 72 Analyse data Graphical displays The reverberation time graphical display includes side-by-side graphs of the reverberation time spectrum (left) and the decay (right). The reverberation time spectrum shows the room average as a solid line and position averages as dashed lines. The shaded area represents the range of position averages. The decay graph shows the decay for the frequency selected on the reverberation time spectrum.

  • Page 73: Levels Measurement View

    Analyse data Tabular display The table shows the average reverberation time in bold, with the reverberation times for each position nested below. The table also includes information about quality indicators, a checkbox which allows you to include or exclude positions in the total average, and links which indicate reused measurements and give information about the original meas- urement.

  • Page 74: List View

    Analyse data Reference curve increment Use the Calculation settings group (in the panel on the right) to change the reference curve increment between 1 dB and 0.1 dB. Generally, you will use an increment of 1 dB for calculating results, and an increment of 0.1 dB for evaluating uncertainty.

  • Page 75: Calculation Settings

    Analyse data Reverberation time measurements For reverberation time measurements using the interrupted noise method with more than one decay at each position, the list view shows the individual decays. Exclude markers Use the list view to add exclude markers in the time profile. Click and drag to select a portion of the measurement in the time profile, then use the context-senstive menu to add a marker.
  • Page 76 L2 is made and quality indicators mark where corrections have been made. If L2 – B2 < 6 dB and you are using HBK 2755 Smart Power Amplifier, you can set up the project to make measurement in serial. See Serial measurements for more information.
  • Page 77 Analyse data Ensemble averaging Enable or disable ensemble averaging. Ensemble averaging: The average reverberation time in a room is calculated by averaging the decay curves and then calculating the reverberation time for the average decay. Ensemble averaging produces average parameters (such as T20) that are calculated based on the ensemble averaged decay. Average decays can be viewed in rever- beration time displays.
  • Page 78 Analyse data Room background noise tests The Room background noise setup group of settings includes settings for the evaluation of background noise levels. Room background noise for more information. Result parameter Choose the parameter with which to compare the measured background noise spectrum: NC (noise criteria) curves NR (noise rating) curves RC (room criteria) curves...

  • Page 79: Generate A Report

    GENERATE A REPORT Building Acoustics Partner generates custom reports that conform to the requirements of the standard used. A report can include the results for one or more partitions (sound insulation tests) or a single room (room background noise tests). Report settings The Report settings group in the panel on the right allows you to customize reports, including the option to upload sig- nature and logo files.
  • Page 80 Generate a report Create a PDF In the PDF preview, the Report preview toolbar includes tools to magnify, rotate and change the view (one or two pages at a time), as well as tools to print or save the report. In the toolbar: Print to PDF (or print directly to a printer).

  • Page 81: Supplementary Information

    SUPPLEMENTARY INFORMATION Topics to support sound insulation tests using Building Acoustics Partner: Calibration check Download the apps Multiple instruments Listening to audio Building acoustics metadata Measurement reuse Low-frequency measurements Serial measurements Room background noise External devices Annotations Topics about using the Building Acoustics Partner PC app: Application menu Open a project Export data...
  • Page 82 Hint: You can respond to the calibration dialog using the mobile app if you are using B&K 2245 with firm- ware versions greater than 1.1.3.1653 or HBK 2255 with firmware versions greater than 1.2.1325. 5. The calibration check will have one of two results: Pass: The measured sound level is within tolerance.
  • Page 83 Supplementary information 6. Exit the calibration check. Calibration history To view the history of calibrations and calibration checks, go to: Menu > Calibration history. Calibration settings Menu location: Menu > System settings > Advanced settings > Calibration. Automatic calibration check By default, the instrument is set to perform a calibration check automatically when it detects the constant sound level produced by the calibrator.

  • Page 84: Multiple Instruments

    Supplementary information To use a different calibrator and set a custom calibration level: 1. Go to: Menu > System settings > Advanced settings. 2. Enable the Service mode setting. 3. Go to: Calibration. 4. Go to: Calibrator. 5. Select Custom. 6. Use Custom calibrator no. to add the calibrator's serial number. 7.
  • Page 85 Supplementary information In the mobile app On the Measurement tab: The L2 measurement displays as the reference curve (L2@Pos) during the meas- urement, which allows you to view both L1 and L2 measurements in real time. You can use the mobile app to open and edit measurements made with the primary instrument, but you will not be able to open or edit measurements made with the secondary instrument.

  • Page 86: Listening To Audio

    Audio recordings HBK 2255 can record listen-quality audio while measuring. If the BZ-7451 licence is installed and enabled on HBK 2255, the instrument can record analysis-quality audio while meas- uring. The sound signal is recorded as 24 bit samples at 65536 Hz.

  • Page 87: Building Acoustics Metadata

    Move the cursor or click in the audio bar to skip around in the recording. Building acoustics metadata When HBK 2255 is in the Building acoustics setup mode, the instrument is configured with predefined metadata. The mobile app uses the metadata to manage the measurements in your sound insulation test for you. However, the metadata makes it easy for you to make and manage your sound insulation measurements using only the instrument, with no app connected.
  • Page 88 Supplementary information If the mobile app is in pocket mode during measurements, the mobile app automatically maintains metadata and man- ages the measurement data accordingly. If the mobile app is minimized during measurements and metadata is maintained, measurement data imports auto- matically according to the metadata when the mobile app is opened again.

  • Page 89: Measurement Reuse

    Supplementary information 3. If you are importing into a project, review its Measurement plan settings to make sure they match the meas- urements you are about to import. 4. Select the measurements you want to import. 5. Tap Import. 6. Save the project. As with the mobile app, measurements with missing or inconsistent metadata trigger a warning and an import wizard.

  • Page 90: Low-Frequency Measurements

    Supplementary information Measurement reuse during a test Reusing measurements affects the measurement process. When reuse is automatic Measurements are listed and applied in the measurement overview. For planned measurements, the mobile app will skip measurements at positions where a measurement is reused.
  • Page 91 Supplementary information ISO 16283 To enable settings for the low-frequency procedure in Building Acoustics Partner: Standard = ISO 16283 Bottom frequency = 50 Hz At least one partition with a receiving room with a volume less than 25 m must be set up in the project. For ISO 16283, the source positions used for the default procedure should also be used for the low-frequency pro- cedure.

  • Page 92: Serial Measurements

    Sometimes an adjustment to the gain setting on the amplifier can increase the signal-to-noise ratio, which can correct the problem. However, if the gain setting on HBK 2755 is within 3 dB of maximum power, you will need to make serial measurements.

  • Page 93: Room Background Noise

    Supplementary information The image shows a magnified view of the mobile app interface for selecting frequency bands to measure serially. You can quickly see the selected band is below the 6 dB level, and it is the only band that has been selected. You can over- ride the selections of the mobile app.
  • Page 94 Supplementary information Method Measurements Sometimes only the loudest position is measured, other times a room average may be used (measure at multiple fixed points or along a traverse). Avoid measuring at the centre of the room or within 1 m of a wall. Measurements are frequently made at the typical ear level for people in the room, that is seated or standing (in general, in the 1.2 to 1.8 m range).

  • Page 95: External Devices

    In the mobile app, the External devices page allows you to manage connections to devices other than the instrument, specifically HBK 2755 Smart Power Amplifier. When the mobile app and amplifier are connected, the mobile app can con- trol the amplifier during sound insulation tests.
  • Page 96 Supplementary information It is always a good idea to add annotations to your measurements. For example, they can help you and your colleagues identify measurements at a later date and provide valuable information about the context of a measurement. Annotations in the mobile app You can make annotations before, during and after measurements.

  • Page 97: Application Menu

    Supplementary information Annotations in the PC app Attached annotations Use the Annotations window (in the panel on the right) to view and edit attached annotations. 1. Select a single room or partition, or a group of rooms or partitions in the project browser. 2.
  • Page 98 Supplementary information Project tools Access tools to create a new project, open a project or save a project, and learn their keyboard shortcuts. Hint: Open a project from the application menu to choose from a list of recent projects. Application options The Options tab opens settings specific to the application.

  • Page 99: Open A Project

    Supplementary information Coverage factor Expanded uncertainty, U, is calculated by U = ku, where k is the coverage factor and u is the standard deviation. Confidence level, % Coverage factor, k Two-sided test One-sided test 1.00 1.28 1.65 1.96 97.5 2.58 99.5 3.29 99.9 99.95...
  • Page 100 Supplementary information 4. Choose the format into which you want to export the measurement data: Excel Workbook (*.xlsx) File extension *.xlsx is compatible with Microsoft Excel 2007 and newer. Tab separated values (*.txt) 5. If you are exporting to a workbook, you have the option to use a master file. When you export a measurement to a workbook, master files tell the PC application what to do with the data.

  • Page 101: Import From Measurement Partner Suite

    Supplementary information How to create master files You can create your own (custom) Microsoft Excel files that define the data you wish to export. This can be used to filter your measurement data in the exported file, to perform custom calculations or to create graphs automatically. 1.
  • Page 102 Supplementary information 1. Decide where you want the data to go: To an existing project: Open the Building Acoustics Partner project before you export from MPS. To a new project: You do not need to start the Building Acoustics Partner PC application before you export.

  • Page 103: About The Instrument

    ABOUT THE INSTRUMENT Hardware interface The microphone and preamplifier are at the top of the instrument. HBK 2255 has a removable microphone preamplifier and supports TEDS (transducer electronic data sheet). is the power/menu/reboot button. Press and hold the button to power the instrument on or off. When the instrument is on, press the but- ton briefly to open the menu.
  • Page 104 About the instrument is the stop/reset button. Press the button once to stop a measurement. At this point, averaged measurement parameters will stop updating and you can review the results. Press the button again to clear the results and reset the instrument for the next measurement.

  • Page 105: Instrument Gui

    About the instrument The light ring is colour-coded to reflect the status of the instrument. The light ring is solid green while measuring. The light ring flashes yellow slowly while idle or quickly while paused (measuring). The light ring flashes red quickly for intermittent overloads. The light ring is solid purple for latched overloads.
  • Page 106 About the instrument When idle, the instrument displays the current time (to the left) and input settings (to the right). : Indicates that the clock is estimated to be more than 2 s wrong. : Indicates that Sound field is set to Free-field and there is not a windscreen. : Indicates that Sound field is set to Free-field and there is a windscreen.
  • Page 107 About the instrument In the middle is the measurement display. There are views for broadband para- meters (SLM view and List view), spectrum parameters (Spectrum view), rever- beration time measurements (Reverberation time view) and a view for information about your data (About data view). Press briefly to scroll through measurement displays.
  • Page 108 About the instrument Reverberation time view displays the reverberation time measurement. Press and hold to move the cursor in the display. The readout above the graph shows the location of the cursor and its decibel level. Press and hold auto-scale the Y-axis to fit the data. For very low or very high sound levels, you will see indicators.

  • Page 109: Web Server Display

    About the instrument The menu Use the buttons on the instrument to interact with the menu. : Open / close the menu; open a response dialog; confirm a setting in a response dialog; enable / disable parameter selection boxes. : Navigate up a list; increment a value in a response dialog. : Navigate down a list;...
  • Page 110 About the instrument Procedure 1. Connect the instrument to a power source. indicates that the battery is charging with a readout of the percentage charged. 2. Disconnect the power source to stop charging. Approved power sources Mains Base station (the base station is powered via mains) Computer Power bank Status...

  • Page 111: Fix An Unresponsive Instrument

    HBK 2255 is designed to be used with different combinations of microphone cartridges and microphone preamplifiers, which enables the instrument to perform a variety of applications. HBK 2255 uses TEDS (transducer electronic data sheet) to set the attached microphone cartridge/preamplifier pair automatically. If you change the microphone cart- ridge/preamplifier pair, the instrument will change the Microphone setting according to the TEDS information of the new pair.

  • Page 112: Teds, Microphones And Hbk 2255

    Disabled: Specify the windscreen manually under Windscreen type. Frequency range HBK 2255 has a few options for extending the lower limit of the frequency range of your measurements. The options available will vary according to the licences installed and enabled on your instrument.
  • Page 113 About the instrument Microphones supported by HBK 2255 Below is a list of all Brüel & Kjær microphone cartridges, microphone preamplifiers, and microphone cart- ridge/preamplifier combinations which can be used with HBK 2255. 1/2-inch Microphone Preamplifier Type 2669 1/4-inch Microphone Preamplifier Type 2670...

  • Page 114: Microphone Database

    You can only access the microphone database on the instrument: Menu > System settings > Advanced settings. HBK 2255 has a detachable microphone preamplifier. The instrument can be used with different combinations of micro- phone cartridges and microphone preamplifiers. The instrument uses TEDS to detect the attached microphone and add new microphones to the microphone database.
  • Page 115 You cannot delete the microphone that the instrument is currently set to use. For HBK 2255, the ability to edit or delete microphones in the database depends on the TEDS scenario which applies to the attached microphone/preamplifier pair. If TEDS only contains information about the microphone preamplifier, it is possible to edit information about the microphone cartridge and/or delete the microphone.

  • Page 116: Audio Recording

    Recording quality HBK 2255 can record listen-quality audio while measuring. If the BZ-7451 licence is installed and enabled on HBK 2255, the instrument can record analysis-quality audio while meas- uring. The sound signal is recorded as 24 bit samples at 65536 Hz.
  • Page 117 The Graph parameter setting defines the parameter for the bar graph; that is, the instantaneous (or fast) display of instantaneous sound levels. Parameter (Spectrum view) The Parameter setting defines the parameter for the spectrum display; that is, the display of the sound level for each frequency band. HBK 2255 can display two parameters.

  • Page 118: Regional Settings

    The range that you define should match the dynamics of the signal you are measuring. In other words, it should include all the sound levels that are present. Lower display limit, Higher display limit (HBK 2255: Spectrum view) Together, the Lower display limit and Higher display limit settings define the display range on the X-axis. This allows you to exclude frequencies from the spectrum view which are not of interest.
  • Page 119 Measurement units: Wind speed, temperature and dimensions HBK 2255 works with weather station kits MM-0316-A and MM-0256-A, which are based on Vaisala weather stations. The measurement unit settings allow you to choose your preferred measurement unit for wind speed, temperature and dimensions.

  • Page 120: Power Management

    About the instrument Power management Use the Power management settings to switch off the screen or instrument after periods of inactivity. These settings can be helpful if you want to maximise battery life for long, unattended measurements. Menu location: System settings > Power management. Switch screen off after Use this setting to switch off the screen on the instrument automatically after a period of inactivity (that is, when you are not pushing its buttons).

  • Page 121: Network Settings

    About the instrument Procedure: 1. Go to: Backup settings > Backup. 2. Select Disabled. 3. Enter the host name or IP address of the device or network (so the instrument can find it). 4. Enter the user name and password (so the instrument can access the device or network). 5.
  • Page 122 About the instrument Add a nickname using the mobile app 1. Tap Nickname. 2. Use the keypad to enter a nickname. 3. Tap Done. Hint: You can also use emojis! Add a nickname using the instrument 1. Select Nickname. 2. Use the arrow keys to enter a name. 3.
  • Page 123 About the instrument Web server display Web server display is a setting that allows you to view the instrument GUI on a web browser that is connected to the same network as the instrument. This can be useful if more than one person wants to be able to monitor a meas- urement from a distance.

  • Page 124: External Devices

    1. Select Reset network settings. 2. Select Yes. External devices For HBK 2255, the External devices setting includes settings that allow you to output the analog signal and to connect the instrument to a weather station. Voltage output for information about how to output the analog signal.

  • Page 125: Voltage Output

    GPS coordinates (if enabled). For HBK 2255, the Metadata setting allows you to create custom metadata. Custom metadata is stored with the meas- urement and supported in the Enviro Noise Partner and Building Acoustics Partner PC applications. If you export your measurement data from the PC application, the export file includes the custom metadata.

  • Page 126: Data Explorer

    About the instrument This is the name you will see when prompted to edit/confirm metadata before saving each measurement. 4. Use the Type setting to define the format of the metadata. Choose Text for metadata which consists of letters, numbers, symbols and spaces. Choose Number for metadata which consists of numbers only.
  • Page 127 About the instrument Options for date folders In the Data folder In the Trash folder Recover: Sends the folder and its contents to the Open: Opens the folder. Data folder. Move to Trash: Moves the folder to the Trash Open: Opens the folder. folder.

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