BRUEL & KJAER 2236 A-008 User manual

bb090813.book : Front Black 3
October 1996
Brüel & Kjær BB0908–13
Precision Integrating
Sound Level Meter
Type 2236 A–008
Type 2236 B–008
Type 2236 C–008
Type 2236 D–008
With software version 2.1 or higher

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0–4 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
User Manual
Trademarks
IBM is a registered trademark of International Business Machines
Inc., USA
Copyright © 1993, 1996, Brüel&Kjær Sound & Vibration
Measurement A/S
All rights reserved. No part of this publication may be reproduced
or distributed in any form, or by any means, without prior consent
in writing from Brüel & Kjær Sound & Vibration Measurement A/S,
Nærum, Denmark.

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BB0908–13 0–5 Precision Integrating Sound Level Meter Type 2236
User Manual
4
1
Contents
Describes the sound level meter and its general operating principles.
A familiarization guide which explains, step by step, a typical
measurement.
How to prepare the sound level meter for measuring.
How to calibrate and measure with the sound level meter.
What you are able to do with your results.
The specifications and information regarding other equipment
available for use with the sound level meter.
Service and repair of the sound level meter.
Explains specific terminology used in the manual and contains
instructions on how to control the sound level meter from a
computer.
Useful Information
2
An Example Measurement
3
Setting Up the SLM for Measurement
Measuring
5
Storing and Transferring Results
6
Specifications
7
Service and Repair
8
Appendices

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User Manual
Index
Fold
Out
Controls, Display and Sockets
An overview of the sound level meter’s pushkeys, controls and main
display.

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BB0908–13 1–1 Precision Integrating Sound Level Meter Type 2236
User Manual
Chapter 1
Useful Information
1.1 About this Manual.............................................................. 1 – 2
1.2 About the Type 2236 Sound Level Meter................. 1 – 2
Parameters......................................................................... 1 – 2
Settings .............................................................................. 1 – 3
Data Operations ................................................................ 1 – 6
Memory .............................................................................. 1 – 8
1.3 Practical Hints...................................................................... 1 – 9

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Chapter 1 – Useful Information
About this Manual
1–2 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
User Manual
1.1 About this Manual
Figures are used to guide you through using the pushkeys.
Please note the following when using the figures:
n×Press this pushkey n times
OK Press this to save any changes made in connection with
the Settings or 〈Data〉pushkeys
NO Press this to return to the screen indicated without sav-
ing any changes made
1.2 About the Type 2236 Sound Level
Meter
1.2.1 Parameters
Precision Integrating Sound Level Meter Type 2236 is a Type
1 sound level meter complying with BS 5969 and BS 6698. It
can measure the following parameters:
●MaxL: maximum SPL since the last reset
●MinL: minimum SPL since the last reset
●MaxP: maximum Peak level since the last reset
●Peak: maximum Peak level in 1s interval
●SPL: maximum RMS level in 1s interval (according to
IEC 651)
●Leq: equivalent continuous sound level (Leq according to
IEC 804)
●SEL: Sound Exposure Level (if A-weighted, then = LEA,
according to IEC 804)
●LEPd: Daily Personal Noise Exposure Level (see section
8.2)
●Ovl: Input signal overloading instrument (% of the meas-
urement time)

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About the Type 2236 Sound Level Meter
BB0908–13 1–3 Precision Integrating Sound Level Meter Type 2236
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In addition, Precision Integrating Sound Level Meter Types
2236 C–008 and 2236 D–008 contain 1/1-octave filter sets
between 31.5Hz and 8kHz which comply with BS 2475 (1964).
They can measure all the above-mentioned parameters in
each of the filter bands.
1.2.2 Settings
Checking and Changing the Settings
The sound level meter’s Settings are additional to the basic
measurement set-up. They are very useful and are based on
a very simple principle (see the example in Fig. 1.1). There
are ten of them in all:
●Auto Logging
●Calibration
●Peak Weighting
●Date and Time
●Auto Start
●Change Range Reset
●Contrast
●Exposure Time
●Interface
●Output Formats
Checking
You can check the first of the sound level meter’s Settings by
pressing the 〈Show〉pushkey. You can then step through
them by pressing 〈Show〉. However, the Settings are cyclic
and you can step forwards and backwards through them us-
ing Parameter 〈▲〉and 〈▼〉, respectively (see Fig. 1.1).
Changing
When you reach a Setting you want to change, press 〈Edit〉.
A cursor ( ) appears on the first set-up line you can change.

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About the Type 2236 Sound Level Meter
1–4 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
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If there are other set-up lines on the screen, you can move
the cursor to them using Level 〈▲〉and 〈▼〉.
When the cursor is on the set-up line of the Setting you want
to change, press Parameter 〈▲〉and 〈▼〉to step through
the available parameters. You can also step through them by
pressing 〈Edit〉(see Fig. 1.1).
When you have the set-up you desire for that Setting, press
〈OK〉to save the changes and check the changed Setting. An
accept cursor (■) replaces the edit cursor ( ) to show that the
sound level meter has accepted the change.
If you change a Setting by mistake, press 〈NO〉instead of
〈OK〉to revert to its previous set-up.
Fig.1.1 Principle of checking and changing the sound level meter’s Set-
tings
931007/1e
Edit
Edit
Parameter
Level
Level or Parameter
Show or Parameter
Show
Parameter ▼
▼▼
▼
▼
▼
Previous
Setting
Previous
parameter
Next
Setting
Next
parameter
AUTO LOGGING
-every 1 s.
to log
▼
AUTO LOGGING
-every 1 s.
to log
30 .... 110
00:00:00
F SPL 58.6 dBA
(Leq MaxL MaxP)
(Leq MaxL MaxP)

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Chapter 1 – Useful Information
About the Type 2236 Sound Level Meter
BB0908–13 1–5 Precision Integrating Sound Level Meter Type 2236
User Manual
Fig. 1.2 shows an overview of the available Settings.
Fig.1.2 An overview of the sound level meter’s Settings
930721/2e
30 .... 110
PAUSE 00:00:00
F SPL 58.6 dBA
OUTPUT FORMATS
INTERFACE
EXPOSURE TIME
CONTRAST
PEAK WEIGHTING
DATE/TIME
AUTO START
CHANGE RANGE
OK Show Show
Show
OK OK
Show OK
Show OK
Show OK
Show OK
Show
OK
NO
Show
OK Show
OK Show
AUTO LOGGING
CALIBRATION
NO
NO
NO
NO NO
NO
NO
NO
NO

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Chapter 1 – Useful Information
About the Type 2236 Sound Level Meter
1–6 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
User Manual
Fast Edit
In addition to the normal way of changing the set-up of a
Setting (that is, pressing 〈Show〉, stepping through to the
desired Setting and pressing 〈Edit〉), you can also use two
pushkeys together to “fast edit” a Setting (that is, go directly
to a Setting with the edit cursor).
If you press 〈Edit〉and, within 3 seconds, the pushkey indi-
cated in Table 1.1, the selected Setting appears with the edit
cursor ( ). You can now check and change the set-up of the
Setting as described earlier in this section. When you have
finished changing the Setting, pressing 〈NO〉or 〈OK〉, how-
ever, returns you to the main screen.
1.2.3 Data Operations
The sound level meter’s 〈Data〉pushkey allows you to print
your measurement results (data) and control the sound level
meter’s memory. It operates on a similar principle as its
Settings (see section 1.2.2) except that you press 〈Data〉in-
stead of 〈Show〉. In addition, the sound level meter returns
to the main screen after you have accepted changes to the
Fast Edit Pushkey (Edit +) ... ... Goes to Setting
Level ▲or ▼
Parameter ▲or ▼(Disp. param.: Peak, MaxP)
Parameter ▲or ▼(Disp. param.: LEP,d)
Data
OK
Calibration
Peak Frequency Weighting
Exposure Time
Output Formats
Change Range with Reset
Contrast
Auto Start
Status (only via Fast Edit)
Table 1.1 Fast edit pushkeys and the Settings accessed Where display
parameters are shown in parenthesis (for example, (Disp. par-
am.: LEP,d)), then the display must be showing the indicated
parameter (in this example, LEP,d) when the Fast Edit keys are
pressed to go to the indicated setting (in this example, Exposure
Time).
▼
0
▼

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BB0908–13 1–7 Precision Integrating Sound Level Meter Type 2236
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selected operation. There are four data operations, each with
its own screen:
●Print
●Store
●Recall
●Erase
Fig. 1.3 shows an overview of the data operations.
Fig.1.3 An overview of the data operations available via the Data push-
key
930791/2e
OK
Data
Data
OK
Data
30 .... 110
PAUSE 00:00:00
F SPL 58.6 dBA
PRINT
STORE
Data
OK
OK
Data
ERASE
RECALL
NO
NO
NO
NO

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About the Type 2236 Sound Level Meter
1–8 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
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1.2.4 Memory
The sound level meter has three types of memory:
●Buffer
●Log
●Memory
Buffer
Contains the set-up and all results for the current measure-
ment (i.e. since the last reset) – see section 1.2.1. From these,
the Overall Results are calculated. The buffer is updated once
a second.
Log
Contains the automatically Logged Results (see Chapter 5):
●Leq
●MaxL
●MaxP
●measurement time of results
Precision Integrating Sound Level Meter Types 2236 A–008
and C–008 can contain up to 21600 sets of results (i.e. up to
64800 results with their measurement times). This is enough
to log, for example, 6hours of Leq, MaxP and MaxL values
logged every second.
Precision Integrating Sound Level Meter Types 2236 B–009
and D–009 can contain up to 86400 sets of results (i.e. up
to 259200 results with their measurement times). This is
enough to log, for example, 24hours of Leq, MaxP and MaxL
values logged every second.
Memory
Contains the Overall Results which you have manually stored
in a Record together with the set-up. Can contain up to 40
Records.

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Chapter 1 – Useful Information
Practical Hints
BB0908–13 1–9 Precision Integrating Sound Level Meter Type 2236
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Overall Results consist of:
1.3 Practical Hints
The sound level meter is designed as a self-contained unit to
meet the requirements given in IEC 651 and similar national
standards. However, some of the requirements given in the
standards are based on measurements of pure tones under
free field conditions. Practical measurements under similar
conditions require the following extra precautions:
●Do not stand close to the sound level meter
●Do not use a windscreen or protective cover
●Using a microphone extension cable, increase the dis-
tance between the microphone and any objects which can
cause disturbances
The influence of your presence on the measurement can easily
be checked by changing the distance between you and the
microphone and observing the change in the measured sound
pressure level. If your position influences the measurement
result, then use a microphone extension cable or spatially
average your measurements (that is, measure at several dif-
ferent locations and average the results). Note that, when
dealing with pure tones, a small change in the position of the
●MaxL
●MinL
●MaxP
●Leq
●SEL
●LEP,d
●Exposure Time
●Ovl
●Frequency weighting of RMS
signal
●Frequency weighting of Peak
signal
●Time weighting
●Measurement range
●Elapsed measurement time
●Start date and time of meas-
urement
●Number of pauses during
measurement

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Practical Hints
1–10 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
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microphone can influence the result just as much as your
physical presence.
Fortunately, the combination of free sound field and pure
tones is very rare. With sound coming from several directions
and as you are measuring over a broad frequency band, the
influence of the sound level meter’s housing, tripod and user
becomes insignificant, and the above precautions need not be
taken.
Figs. 6.8 and 6.9 show the influence of Tripod UA 0801 and
Protective Cover UA 1236 under free field conditions and with
pure tones.

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BB0908–13 2–1 Precision Integrating Sound Level Meter Type 2236
User Manual
Chapter 2
An Example Measurement
2.1 Introduction ........................................................................... 2 – 2
2.2 Making a Measurement ................................................... 2 – 2

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Chapter 2 – An Example Measurement
Introduction
2–2 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
User Manual
2.1 Introduction
This chapter guides you through the basic functions of the
sound level meter by instructing you on how to make a noise
measurement in a free sound field. You can find further in-
formation on the various steps in the relevant sections of the
User Manual.
It is a good idea to have the fold-out back cover open so that
you have an annotated illustration of the sound level meter
in front of you while you follow the example measurement.
We have assumed that the sound level meter is switched off
and has not been used before following these instructions. If
it has, ensure that you are using the default set-up (see
section 3.3) before following the steps below.
We have also assumed that you will calibrate the sound level
meter with Sound Level Calibrator Type 4231 and that you
will print out your results using Serial Printer WQ 1138.
2.2 Making a Measurement
Switching On
1. Press .
The sound level meter switches on. After a self-test, the
sound level meter is set up in Pause mode in the default
set-up. The quasi-analogue scale shows the input signal
to the preamplifier and displayed parameter shows the
current SPL. The buffer, log and memory are empty.
Since the displayed parameter (SPL) is an RMS param-
eter, you can see the frequency weighting of the RMS
signal (shown in the bottom right-hand corner of the
screen). See the fold out back cover for more details of
the main screen.

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Chapter 2 – An Example Measurement
Making a Measurement
BB0908–13 2–3 Precision Integrating Sound Level Meter Type 2236
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Calibrating the Sound Level Meter
2. Press 〈Show〉.
The screen shows the default Auto Logging screen.
3. Press Parameter 〈▲〉.
The screen changes to the Calibration screen. The current
calibration factor is shown.
4. Press 〈Edit〉.
The screen shows the calibration set-up (see Fig. 2.1).
5. Read the correct calibration level from the calibrator’s
calibration chart and use Parameter 〈▲〉and 〈▼〉to set
the sound level meter to this level.*
6. Fit the calibrator onto the sound level meter and rest the
sound level meter on a table or other flat surface. Ensure
that the calibrator fits snugly on the microphone.
7. Switch on the calibrator.
The calibrator emits the 1kHz calibration signal.
8. Press 〈OK〉.
* Sound Level Calibrator Type 4231 provides a nominal calibration signal of 94dB at 1kHz.
However, each calibrator is slightly different. It is, therefore, important to set the calibration
level to the one given on the calibration chart for the calibrator used.
Fig.2.1 The calibration set-up screen
930989/1e
CALIBRATION
Calibr. level:
94.0 dB
▼

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Chapter 2 – An Example Measurement
Making a Measurement
2–4 Brüel & KjærPrecision Integrating Sound Level Meter Type 2236
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The sound level meter checks the calibration signal
against the calibration level you set in step 5. It then
asks if you want to calibrate according to the expected
level.
9. Press 〈OK〉.
The sound level meter calibrates itself according to the
calibration level you set in step 5 and returns to the
Calibration screen. The new calibration factor is shown.
10. Press 〈OK〉.
The sound level meter returns to the main screen.
Checking the Weightings
11. With sound level meters without filter sets (Types
2236 A–008 and 2236 B–008), press 〈Frequency Wt.〉
three times.
The frequency weighting of the RMS signal (displayed in
the bottom right-hand corner of the screen) changes
through the three available weightings.
12. With sound level meters with filter sets (Types
2236 C–008 and 2236 D–008), press 〈Frequency Wt.〉
twelve times.
The frequency weighting of the RMS signal (displayed in
the bottom right-hand corner of the screen) changes
through the three available total weightings and the nine
available octave filters (displayed at the left-hand side of
the screen under the quasi-analogue scale). It then re-
turns to the original frequency weighting of the RMS
signal.
13. Press 〈F/S〉twice.
The time weighting displayed in the bottom left-hand
corner of the screen changes through the two available
weightings.

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Making a Measurement
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Setting up the Sound Level Meter to Log
14. Press 〈Show〉.
The screen shows the default Auto Logging screen (see
Fig. 2.2). You can see that the sound level meter is set
up so that it doesn’t store Logged Results in its log.
15. Press 〈Edit〉.
You can now set up the sound level meter to automatically
store Logged Results in its log.
16. Press Parameter 〈▲〉.
The screen changes to the Auto Logging set-up screen
shown in Fig. 2.3. You can see that the sound level meter
is set up to automatically store Logged Results (Leq,
MaxL and MaxP) in its log every 1s.
Fig.2.2 The default Auto Logging set-up screen
Fig.2.3 One of the Auto Logging set-up screens
930990/1
AUTO LOGGING
Off
930992/1e
AUTO LOGGING
to log
-every 1 s.
▼
(Leq MaxL MaxP)

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17. Press 〈OK〉twice.
The sound level meter returns to the main screen.
You are now ready to start an A-weighted measurement
of noise with a FAST time weighting. Leq, MaxL and
MaxP will be automatically logged into the sound level
meter’s log.
Measuring
18. Select an appropriate measurement range using Level
〈▲〉or 〈▼〉.
An appropriate measurement range is when the signal
remains on the quasi-analogue scale at all times and no
overload (indicated by + in the upper right-hand corner
of the screen) occurs.
Note: It is important to select an appropriate measure-
ment range before starting to measure as, if you change
the range, the sound level meter will reset (see section
3.9).
19. Press .
This clears the sound level meter’s buffer of results and
sets the elapsed time to zero.
20. Press .
The sound level meter starts measuring. The timer on
the right-hand side of the screen starts counting the
elapsed measurement time. The A-weighted SPL is
shown at the bottom of the screen. After each second, the
Leq, MaxL and MaxP are transferred to the sound level
meter’s log.
21. Use Parameter 〈▲〉or 〈▼〉to look at the various pa-
rameters available.
The quasi-analogue scale always shows the SPL, regard-
less of the selected parameter. Note that, when a Peak
parameter is selected, the frequency weighting of the
Peak signal is shown. Note also that, when changing the
parameter, the sound level meter does not reset.
▼
0
▼