BRUEL & KJAER 4185 User manual

USER MANUAL
EarSimulatorforTelephonometry
Type4185
BR 2309 – 11
English
www.bksv.com ©Brüel&Kjær.Allrightsreserved.
ËBR-2309---CÎ BR 2309 – 11

BR 230911
September2015
www.bksv.com
EarSimulatorforTelephonometry
Type4185
UserManual

HealthandSafetyConsiderations
This apparatus has been designed and tested
in accordance with IEC/EN 61010–1 and
ANSI/UL 61010–1
Safety Requirements for
Electrical Equipment for Measurement,
Control and Laboratory Use
. This manual
contains information and warnings which
must be followed to ensure safe operation and
to retain the apparatus in safe condition.
SafetySymbolsandSignalWords
Used
The apparatus will be marked with
this symbol when it is important that
you refer to the associated danger
or warning statement given in this
manual
The manual uses this symbol when a
danger or warning statement is
applicable
Hazardous Voltage/Electricity. Both
the apparatus and manual use this
symbol when there is a risk for shock
or electrocution
Hot Surface. This manual will use
this symbol when there is a risk for
burning or scolding
Earth (Ground) Terminal. The
apparatus will be marked with this
symbol when applicable
Protective Conductor Terminal. The
apparatus will be marked with this
symbol when applicable
Alternating Current. The apparatus
will be marked with this symbol
when applicable
Danger Signals an imminent hazardous
situation, which, if not avoided, will
result in death or serious injury
Warning Signals a possibly hazardous
situation, which, if not avoided, will
result in death or serious injury
Caution Signals a hazardous situation,
which, if not avoided, could result in
minor or moderate injury or
damage to the apparatus
Notice Signals a situation or practice that
requires attention, but does not
directly result in personal injury if
ignored
RisksandHazards
ExplosionHazards
Danger: The apparatus is not
designed to be used in potentially
explosive environments. It should
not be operated in the presence of
flammable liquids or gases
ElectricalHazards
Warning: Any adjustment,
maintenance and repair of the open
apparatus under voltage must be
avoided as far as possible and, if
unavoidable, must be carried out
only by trained service
Caution: Switch off all power to equipment
before connecting or disconnecting
their digital interface. Failure to do
so could damage the equipment

MechanicalHazards
Caution: Whenever it is likely that the correct
function or operating safety of the
apparatus has been impaired, it
must be made inoperative and be
secured against unintended
operation
WasteHandling
Brüel & Kjær complies with the EU’s Waste
Electrical and Electronic Equipment
(WEEE) Directive, which issues the
following waste handling instructions:
• Do not dispose of electronic
equipment or batteries as
unsorted municipal waste
• It is your responsibility to
contribute to a clean and healthy
environment by using the
appropriate local return and
collection systems
• Hazardous substances in
electronic equipment or batteries
may have detrimental effects on
the environment and human
health
• The symbol shown to the left
indicates that separate collection
systems must be used for any
discarded equipment or batteries
marked with that symbol
• Waste electrical and electronic
equipment or batteries may be
returned to your local
Brüel & Kjær representative or to
Brüel & Kjær Headquarters for
disposal

Brüel & Kjær has made every effort to ensure
the accuracy of the information contained in
this document. No responsibility is accepted
for any errors or omissions herein. It is the
responsibility of the user to ensure compliance
with any legal or statutory requirements in the
country of use. Data may change, as well as
legislation, therefore you are advised to obtain
copies of the most recently issued applicable
regulations, standards and guidelines.
All descriptions, illustrations and any other
information relating to the product are made by
way of general description, are approximate
only and for the general guidance and
information of the user. They cannot be
construed to imply representation or warranty
as to their accuracy, currency or completeness
and are not intended to form the basis of any
contract.
The information in this document does not
constitute a warranty, representation or
guarantee concerning the suitability or
performance of the product.
Brüel & Kjær shall not be liable for any loss
whether direct, indirect, incidental or
consequential arising from the use of or
reliance upon any of the content of this
document, regardless of whether such content
has been accurate or complete. Brüel & Kjær
will not pay any damages whether for loss or
injury, punitive or otherwise, because of use of
or reliance upon any of the content in this
document.
Brüel & Kjær and all other trademarks, service
marks, trade names, logos and product names
are the property of Brüel & Kjær or a third-
party company. Nothing in this document may
be construed as granting, by implication, or
otherwise any license or right to use any of the
trademarks without a prior written permission
of Brüel & Kjær or the owner of such
trademark.
© Brüel & Kjær. All rights reserved.
Brüel & Kjær Sound & Vibration
Measurement A/S
DK-2850 Nærum · Denmark
For service and support, contact your nearest
Brüel & Kjær Customer Care support team:
Headquarters: [email protected],
[phone]
China (Beijing): [phone]
France: [email protected]m,
[phone]
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[phone]
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The Americas: [email protected],
[phone]
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[phone]
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[phone]
Go to www.bksv.com/contact for contact
information to our other global offices.

Contents
CHAPTER1
Description.........................................................................................1
1.1 What’sintheCase ........................................................................2
1.2 TypicalConfiguration ....................................................................4
CHAPTER2
Calibration..........................................................................................5
2.1 AcousticImpedance......................................................................5
2.2 FrequencySensitivityResponse....................................................6
2.3 AbsoluteSensitivity.......................................................................8
2.4 CalibratingType4185 ...................................................................9
CHAPTER3
HandlingtheEarSimulator............................................................... 11
3.1 AssemblingType4185 ................................................................11
3.2 AdjustingtheEarSimulatorForce ..............................................12
3.3 ProtectingtheEarSimulator.......................................................13
3.4 MoreInformation .......................................................................13
CHAPTER4
AcousticPropertiesoftheCoupler ................................................... 15
4.1 EquivalentDiagrams ...................................................................15
CHAPTER5
Specifications ...................................................................................19
CHAPTER6
Glossary ...........................................................................................21

1EarSimulatorforTelephonometryType4185
UserManual
Chapter1
Description
Fig.1.1 EarSimulatorforTelephonometryType4185
Ear Simulator for Telephonometry Type 4185 isdesigned for telephone
measurements requiring an IEC 60318–1 coupler. Type 4185 converts
the acoustic signal from an earphone into an electrical equivalent that
takes into account the response of the human ear. It enables
electroacoustic measurements on telephone handsets to be carried
out under well-defined acoustical conditions.
Type 4185 fulfils the requirements of Rec. ITU-T P.57 Type 1 and
IEC 60318–1 as well as all relevant ITU-T, IEEE and BS
recommendations.

What’sintheCase
2EarSimulatorforTelephonometryType4185
UserManual
1.1 What’sintheCase
In the carrying case, you receive all the necessary parts for Ear Simulator
for Telephonometry Type 4185:
Fig.1.2 PartsofType4185
• Low-noise Cable AO-0122-D-030, for the miniature sound source (A)
• 4 × Soft Seal YJ-0431 (B)
• Adaptor Sleeve for Acoustic Coupler DB-1164 (C)
• Microphone Cable AO-0419, LEMO to LEMO (D)
•½Condenser Microphone Type 4192 attached to ½Microphone
Preamplifier Type 2669 (E)
• BNC Input Adaptor JP-0145 (F)
• Ring for Acoustic Coupler DB-1160 attached to Acoustic Coupler
UA-1110*(G)
•CouplerDataDisk(H)
*Acoustic Coupler UA-1110 is delivered with 1 × Soft Seal YJ-0431 and
1 × Black Collar YJ-0430 already attached
A
BC
D
E
FGH

Chapter1 – Description
3EarSimulatorforTelephonometryType4185
UserManual
1.1.1 TheAcousticCoupler
Type 4185 consists of an acoustic coupler that has a built-in miniature
sound source for seal checking, a microphone and a preamplifier.
The seal between Type 4185 and the handset under test must be
completely tight. The quality of this seal can be verified using the
miniature sound source located inside the acoustic coupler. This sound
source is a small transducer that can be excited with an external signal
to produce a sound pressure inside the main cavity. If the seal between
the coupler and handset is poor, the sound pressure measured by the
microphone will be considerably lower at low frequencies than if the
seal is tight.
Fig.1.3 SectionalviewoftheacousticcouplerusedinType4185
As shown in Fig. 1.3, the acoustic coupler contains three volumes
acoustically connected in parallel by means of a narrow annular slit and
four parallel holes. The volumes are:
•
V
1= 2.5 cm3
• V
2= 1.8 cm3
•
V
3= 7.5 cm3
The acoustic resistances and inductances of the slit and parallel holes
are given in Chapter 4.
Soft Seal
Sound Source
Measuring Microphone
V3
V2
V1
Black Collar
900339e
Acoustic
Coupler

TypicalConfiguration
4EarSimulatorforTelephonometryType4185
UserManual
1.2 TypicalConfiguration
Type 4185 can be used with a wide range of Brüel & Kjær telephone
test systems. The typical configuration is with Telephone Test Head
Type 4602-B.
In this typical configuration, Type 4185 is mounted directly in the test
head for tests on telephone handset receivers for measuresments on
sealed, supra-aural and supra-concha earphones. The entire ear
simulator assembly is mounted in the upper main plate of the test head
in a spring-loaded mechanism that gives a well-defined and adjustable
force against the earcap. This design, together with the soft seal on
Type 4185, is optimized to prevent acoustical leakage between the
earcap and the ear simulator.
For instructions on using Type 4185 in this configuration, see the user
manual for Test Head Type 4602-B, BE 1273.
Fig.1.4 HardwareoverviewfortelephonetestingusingTestHeadType 4602‐B
130884/1
2735
Power Amplier
4231
Sound
Calibrator
3160-A-042
LAN-XI Module
WL-1324 WL-1325
4185
Ear Simulator
4195
Wideband Ear
Simulator
4602-B Test Head Mouth Simulator
with 4227 Mouth Simulator

5EarSimulatorforTelephonometryType4185
UserManual
Chapter2
Calibration
During manufacture, the ear simulator is calibrated according to
ITU–T Rec. P.57. The acoustic impedance and the frequency sensitivity
response are individually measured as functions of frequency.
The individually measured calibration data is supplied with the ear
simulator – on a calibration chart and the “Coupler Data Disk” CD. The
data is stored in a Microsoft®Excel®workbook.
2.1 AcousticImpedance
The acoustic impedance is defined as the acoustic input impedance of
the ear simulator, seen from the ear reference point (ERP), the reference
point for telephone measurements in most telephone standards. It is
measured using a specially designed impedance probe containing a
built-in high-acoustic impedance sound source and a calibrated probe
microphone. When the impedance probe is mounted on the ear
simulator, the tip of the probe microphone will be positioned exactly at
the ERP. By measuring the sound pressure at the ERP from the high
acoustic impedance sound source, the acoustic input impedance of the
ear simulator can be calculated. The impedance is displayed in decibels
relative to 1 acoustic ohm (1 Pa·s/m3). See Fig. 2.1.

FrequencySensitivityResponse
6EarSimulatorforTelephonometryType4185
UserManual
Fig.2.1 TypicalacousticimpedanceforEarSimulatorType4185andthestandardized
ITU–T Rec.P. 5 7 Type1curvewithwhichType4185complies
2.2 FrequencySensitivityResponse
The frequency sensitivity response is defined as the modulus of the
ratio of output voltage of the ear simulator to input sound pressure at
the ERP. The frequency sensitivity response (also referred to as the
drum reference point (DRP) to the ERP transfer function) is normalized
to0dBat1kHz.Theresponseismeasured under open-ear conditions
by mounting the artificial ear in a large, plane baffle and exposing it to
a plane wave incident perpendicular to the baffle. The sound pressure
at the ERP is then measured using a calibrated probe microphone
together with the output voltage of the ear simulator, each as a
function of frequency. The frequency sensitivity response can then be
calculated as the ratio of the measured output voltage of the ear
simulator to the measured input sound pressure at the ERP. For
practical reasons, the frequency sensitivity response also is measured
970388e
100 200 500 1k 2k 5k 10k
Hz
100
110
120
130
140
150
dB
Acoustic Impedance for Type 4185, re 1 Pa s/m3
ITU-T P.57
Typical

Chapter2 – Calibration
7EarSimulatorforTelephonometryType4185
UserManual
under closed-ear conditions. The frequency sensitivity response is
used as a correction function. Normally the open-ear response is used.
The closed-ear frequency sensitivity response is only used for
diagnostic purposes, for example, to interpret differences between
measurements made on a handset with Type 4185 and with
measurements made with other ear simulators.
Using the open-ear frequency sensitivity response as a correction
function, measurements made on any telephone handset are (by
division with the frequency sensitivity response) referred to the
equivalent sound pressure at the ERP. This is required to calculate
loudness rating or to check results against specifications that are based
on measurements referred to the ERP.
However, for Type 4185, the frequency sensitivity response under open-
ear conditions is practically independent of frequency up to 3 kHz and
the correction is less than 1 dB up to 4 kHz (see Fig. 2.2). Hence, the
frequency dependency is often ignored for Type 4185 – the ear simulator
is considered as measuring at the ERP and the measurements can be
used directly without need for further correction.

AbsoluteSensitivity
8EarSimulatorforTelephonometryType4185
UserManual
Fig.2.2 Open‐andclosed‐earfrequencysensitivityresponsesfortheearsimulator
2.3 AbsoluteSensitivity
The absolute sensitivity at 1 kHz in V/Pa is defined as the modulus of
the ratio of the absolute output voltage of the ear simulator to the
input sound pressure at the ERP. The absolute sensitivity is specified on
the calibration chart for both open- and closed-ear conditions. The
sensitivities can be verified using Sound Calibrator Type 4231.
Normally the calibration level,
P
4231, produced by Type 4231 mounted
on a ½microphone is 94 dB SPL, but if an extra volume is added,
caused for instance by the presence of a coupler unit, the sound
pressure produced by the calibrator is affected.
The required measurement conditions also influence the calibration.
When using the calibrator, the ear simulator is exposed to closed-ear
conditions. Therefore, when calibrating, it is the sensitivity according to
970377/1
100 200 500 2k 5k1k 10k
-20
-10
0
10
20
30
dB
Frequency Sensitivity Response for Type 4185 , re 1 kHz
Open-ear Frequency
Sensitivity Response
Closed-ear Frequency
Sensitivity Response
(Hz)

Chapter2 – Calibration
9EarSimulatorforTelephonometryType4185
UserManual
closed-ear conditions that is measured. As it is the open-ear sensitivity
that is of interest, the calibration data must be transformed to refer to
this situation.
The required sensitivities can therefore be found if the calibration level
of the sound calibrator is corrected. The calibration level must be
corrected by a factor
P
Vcaused by any added volume and, to obtain
the open-ear sensitivity, by a factor
P
(open-closed) to take into account
the change in sensitivity when going from closed-ear to open-ear
conditions.
The corrected calibration level to obtain the open-ear sensitivity is then
given by:
P
4231,corrected (open ear) =
P
4231 +
P
V+
P
(open – closed)
and the corrected level to obtain the closed-ear sensitivity by:
P
4231,corrected (closed ear) =
P
4231+
P
V
2.4 CalibratingType4185
Before assembling of Type 4185, the microphone should be calibrated
using Sound Calibrator Type 4231.*The absolute sensitivity at 1 kHz in
[V/Pa] of Type 4185 as stated on the calibration chart is verified by
applying the calibrator to the ½microphone without the coupler.
*Pistonphone Type 4228 can also be used for calibration.

CalibratingType4185
10 EarSimulatorforTelephonometryType4185
UserManual
Fig.2.3 Sensitivitycalibrationat1kHzusingSoundCalibratorType4231
Note that the microphone and preamplifier can be calibrated as an
assembly without removing the adaptor sleeve (see Fig.2.3).
By using the corrected calibration levels as given in Table 2.1, the open-
or closed-ear sensitivity of the (assembled) ear simulator is obtained.
Table2.1 CorrectedcalibrationlevelsforSoundCalibratorType 4231
Calibratingthe½MicrophonewithSoundCalibrator
Type 4231
To calibrate the microphone, ensure that the standard green adaptor
(UC-0210) is inserted in the middle of the calibrator.
1) Press the microphone into the opening in the calibrator.
2) Press the button on the calibrator.
3) Adjust the sensitivity of the ear simulator to read the correct value.
Note the corrected calibration level from Table 2.1.
4) Remove the calibrator from the microphone.
For detailed information on using the sound calibrator, see its user
manual, BA 5341.
P4231,corrected (openear) P4231,corrected (closedear)
Type 4185 93.8 dB 93.3 dB

11EarSimulatorforTelephonometryType4185
UserManual
Chapter3
HandlingtheEarSimulator
3.1 AssemblingType4185
Ring for Acoustic Coupler DB-1160, Black Collar YJ-0430 and 1 × Soft
Seal YJ-0431 are all supplied already attached to Acoustic Coupler
UA-1110. If UA-1110 and DB-1160 are separate, simply screw them
together. Fit the microphone and preamplifier as follows:
1) Insert Preamplifier Type 2669 into Adaptor Sleeve DB-1164 at the
adaptor sleeve’s small end.
2) Screw Microphone Type 4192 onto the preamplifier body so that
the adaptor sleeve is clamped between the microphone and the
preamplifier.
3) Screw the complete assembly onto the coupler assembly using the
coarse thread on the adaptor sleeve.
Fig.3.1 Assemblyoftheearsimulator
Black Collar
YJ-0430
UA-1110
Ear Simulator for
Telephonometry
4185 Soft Seal
YJ-0431
1/2" Microphone
Preamplier
2669
DB-1164
DB-1160
150322

AdjustingtheEarSimulatorForce
12 EarSimulatorforTelephonometryType4185
UserManual
3.2 AdjustingtheEarSimulatorForce
Using Type 4185 requires sealed conditions, therefore, it is essential for
the measured response that there is no leakage between the handset
earcap and the ear coupler. This can be checked in four ways:
1) With the receiver energized (low frequency), adjust the ear
simulator force until audible sound is at a minimum.
2) With the measurement equipment set up and using a low test
frequency (for example 200 Hz), adjust the ear simulator force until
maximum output from the microphone in the ear simulator is
detected.
3) With the measurement equipment set up, measure the frequency
response repeatedly and adjust the ear simulator force for
maximum low-frequency response (see Fig. 3.2).
4) Use the built-in seal check facility of Type 4185. The procedure is
very similar to using a low test frequency as explained above, but
the built-in sound source of Type 4185 has the advantage of
delivering a constant volume velocity so that the resulting SPL in
the ear simulator is independent of the receiver sensitivity.
ITU-T recommends an application force between 8 and 10 N for
placing earcaps against the ear simulator. An application force higher
than 10 N will affect the performance of the coupler.