BRUEL & KJAER 4100 User manual

English BE 1391 – 13
Sound Quality Head and Torso Simulator
Type 4100 & 4100 D
BE1391-13.fm Page 1 Friday, September 14, 2001 2:11 PM

Revision September 2001
BE 1391 –13
Brüel & KjærSound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Sound Quality Head and Torso Simulator
Type 4100, 4100 D
be139113.book Page i Friday, September 14, 2001 1:50 PM

Brüel & KjærSound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Copyright © 1994 – 2001, 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 Meas-
urement A/S, Nærum, Denmark.
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Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
BE 1391 –13 iii
Contents
1. Introduction ........................................................................................................................... 1
1.1 Introduction...................................................................................................................... 2
1.2 Sound Quality ................................................................................................................... 2
1.3 Subjective Listening Tests................................................................................................. 2
1.4 Systems for Sound Quality Testing .................................................................................. 3
1.5 How to Use this Manual................................................................................................... 5
2. Getting Started.................................................................................................................... 7
2.1 Inventory........................................................................................................................... 8
Main Components ....................................................................................................... 8
Accessories ................................................................................................................... 9
2.2 Construction ..................................................................................................................... 9
Ear Simulator ............................................................................................................... 9
Head, Torso and Neck Ring....................................................................................... 10
2.3 Assembly and Dismantling............................................................................................. 11
Attaching and Removing the Silicone Pinna ........................................................... 11
Adjusting the Neck Ring ........................................................................................... 11
Changing Preamplifier Cables .................................................................................. 12
Mounting and Mounting Holes................................................................................ 12
Scales and Mounting Guides..................................................................................... 12
3. Calibration and Setup.................................................................................................. 15
3.1 Calibration ...................................................................................................................... 16
3.2 Frequency Response Calibration.................................................................................... 17
4. Service........................................................................................................................................ 21
5. Specifications....................................................................................................................... 23
5.1 Specifications –Type 4100 ............................................................................................. 24
5.2 Specifications –Type 4100 D .......................................................................................... 24
5.3 Common Specifications –Types 4100, 4100 D............................................................... 24
5.4 Ordering Information..................................................................................................... 24
Index ........................................................................................................................................... 25
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User Manual
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Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
BE 1391 –13 1
Chapter 1
Introduction
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Chapter 1 —Introduction
Introduction
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Brüel & Kjær
2
1.1 Introduction
Sound Quality Head and Torso Simulators Types 4100 and 4100 D are manikins for
sound quality testing. Type 4100 includes Falcon RangePreamplifiers Type 2669 L
with charge injection calibration facility, while Type 4100 D includes DeltaTron
Preamplifiers Type 2671. Both types use high sensitivity, low noise, ½″Falcon Micro-
phones. Throughout this manual, we refer to both types as Type 4100 or “the simula-
tor”, except where the difference is specifically indicated.
Two microphones, positioned at the entrances to the manikin’s ear canals, simulate
the human ear separation and ensure a signal that includes the interference patterns
caused by the head and upper body. This gives an extremely accurate three-dimen-
sional, binaural recording.
Two moulded-silicone pinna simulators sit around the microphones to provide direc-
tivity patterns similar to the human ear.
The simulator has a sound-dampening fabric cover which slips easily over the mani-
kin’s neck. This assists in changing the reflections and diffraction from the body and
shoulders to obtain the correct directivity.
The position of the head can be adjusted by turning the neck ring so that the head
looks straight forward or slightly down at an angle of 17°.
1.2 Sound Quality
The sound quality of the noise from a product, as perceived by a person, is an
increasingly important factor when assessing the total quality of the product. Objec-
tive measuring methods have shown themselves to be inadequate at identifying the
differences which can be experienced by listening.
This applies to all forms of transport as well as household and office machinery
products: all are increasingly subject to the optimization of their sound quality. Sub-
suppliers of products and components to these industries are often required to in-
clude an acceptable sound quality as a part of the product specifications.
1.3 Subjective Listening Tests
The final evaluation of the sound quality of a product is normally made using a
selected group of people –a jury in a listening test.
To have the jury listen to the sound in reality, for example each jury member driving
a car and then reporting on the sound quality, is both time consuming and costly. To
overcome this, the simulator can be used to make a high-quality binaural recording
of the product’s noise on a DAT recorder. This can then be simultaneously presented
to all members of the jury off-site.
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Chapter 1 —Introduction
Systems for Sound Quality Testing
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
BE 1391 –13 3
However, to avoid bias errors in this process, it is important that the acoustic prop-
erties of the recording and playback are as accurate as possible. Type 4100 therefore
has a frequency response to sounds coming from all directions which closely approx-
imates the direction-dependent human response, and inter-aural time differences
very close to those of the average person.
Sound quality is normally used interactively, for example in the product design
phase, for time and frequency filtering of the played back signals. This allows the
localization of signal components that are important for the subjective experience, or
the simulation of proposed modifications to a test object. These manipulations, to-
gether with ordinary editing of recordings for playback, are often carried out from a
special work station: a PC or a work station built up using a digital signal processor
for signal analysis along with its own storage medium.
1.4 Systems for Sound Quality Testing
Sound quality is an application in which an entire chain of apparatus comprises the
finished system. The better integrated each link in the chain is, the greater its relia-
bility.
Depending on your application, a greater or lesser number of components is required
in order to obtain the results you are after. Fig.1.1 illustrates the basic building
blocks of a sound quality system. All of these building blocks must be accurate and
reliable as the system is no better than the poorest of its components.
Fig.1.1 The basic building blocks of a sound quality system
940603e
Analysis
Playback
conditioning
Recorder Editing
Sound Quality
Head and Torso
Simulator
4100 Signal
Conditioning
and diffuse
field correction
Recording
Playback
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Chapter 1 —Introduction
Systems for Sound Quality Testing
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Brüel & Kjær
4
Recording
Any recording portion of a sound quality system consists of:
●Microphone/transducer
●Preamplifier
●DAT recorder
In the case of Type 4100, the microphone and preamplifier are built into the head
and torso casing.
The simulator is placed in the test environment (automobile, aeroplane, machine
shop) in a position which simulates the position of a person in that situation, and the
sounds around it are recorded using a DAT recorder. When a sufficient interval has
elapsed to give an appropriate spectrum of the sound quality in the given environ-
ment, the recorder is switched off, and the data is ready for playback and analysis.
Playback Systems
Playback systems are used to listen to and analyse the original sound recorded via
the DAT recorder. A minimum configuration consists of the following elements:
●Equalizer
●Integrated amplifier
●Headphones
The equalizer compensates for errors in the diffuse-field response of the headphones,
which may not be ideal. When using Type 4100 (D), the sound is usually recorded
with a flat diffuse-field correction with respect to the entrance to the ear canal. If this
is the case, the headphones should also be corrected to present a flat diffuse-field
response at the entrance to the ear canal. Open or semi-open headphones are recom-
mended.
Analysis
Quite often, the first evaluation of the sound quality of a product, as perceived by
the jury, is not satisfactory. Therefore, the recorded signals from the simulator can
be modified using a PC with a sound quality software program which has a wide
range of time/frequency domain editing and display techniques. The modified signals
can then be compared with the original, by the jury, in a listening test. If the modi-
fied signal is preferred, information on the changes in the sound can be used by the
product designer to obtain –by physical changes –improved sound quality.
Analysis is often performed on sound quality data in order to obtain specialized, non-
subjective kinds of information about the sound. This kind of information can be
used to measure certain parameters with respect to the sound, which have a well-
understood meaning for the specific industry, or it could be used to develop objec-
tive tests which simulate subjective testing.
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Chapter 1 —Introduction
How to Use this Manual
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
BE 1391 –13 5
One set of objective parameters or metrics are those based on a Zwicker Loudness
calculation:
●Loudness
●Sharpness
●Roughness
●Fluctuation strength
1.5 How to Use this Manual
This manual will help you set up and use the Sound Quality Head and Torso Simula-
tor Type 4100, as well as provide you with information about using it in connection
with larger sound quality systems.
Chapter 2 lists the equipment which comes with the simulator, and tells you how to
install and remove the pinna simulator, adjust the head angle, change preamplifier
cables, etc.
Chapter 3 gives information about how to calibrate the simulator.
Chapter 4 contains service information.
Chapter 5 contains the simulators’specifications.
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User Manual
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Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
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Chapter 2
Getting Started
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Chapter 2 —Getting Started
Inventory
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Brüel & Kjær
8
2.1 Inventory
2.1.1 Main Components
Your Sound Quality Head and Torso Simulator comes fully assembled and has its
own calibration chart. It consists of eight main components as shown in Fig.2.1:
●Head (consisting of two halves)
●Neck ring
●Torso
●Microphone/preamplifier assemblies
●Connection cables
●Silicone pinnae
●Absorptive cover for the torso (Fig.2.3)
Fig.2.1 The main components of the Sound Quality Head and Torso Simulator
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Chapter 2 —Getting Started
Construction
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
BE 1391 –13 9
2.1.2 Accessories
A number of accessories are provided with the simulator:
●Calibration adaptor
●Support leg
●Handle
●Tripod mounting adaptor
The use and mounting of these accessories is described in the sections and chapters
which follow.
2.2 Construction
2.2.1 Ear Simulator
The ear simulator has a very simply construction:
●Type 4100 includes two Type 4190–L–002 microphone/preamplifier assemblies
with built-in TEDS, each comprising a ½″Falcon Range Microphone Type 4190
placed in the bottom of the concha, an angle piece and Falcon series Preamplifier
Type 2669 L with charge injection calibration (CIC) facility and LEMO connector
●Type 4100 D includes two Type 4189–A–002 microphone/preamplifier assemblies
with built-in TEDS, each comprising a ½″Falcon Range Microphone Type 4189
placed in the bottom of the concha, an angle piece and a DeltaTron Preamplifier
Type 2671 with BNC connector
An ear-shaped piece of silicone (the pinna), is fitted around the microphone.
Fig.2.2 Cross-section showing the construction of the ear simulator
940368e
Angle piece
Pinna
Preamplifier
Microphone
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Chapter 2 —Getting Started
Construction
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Brüel & Kjær
10
The microphones are mounted in the entrance to the ear canal. This means that,
when played back through headphones, the sound presented at the ear canal of the
listener is the same as the measured sound.
2.2.2 Head, Torso and Neck Ring
The head and torso are connected by a reversible neck ring. This allows two head
positions: one with the head upright and the other with it tilted downwards at an
angle of 17°from the horizontal. This approximates the head position of a person
who is, for example, (i) a passenger in a car, (ii) a person sitting in a concert hall
listening to music, or (iii) a person sitting at a desk, working. Fig.2.3 illustrates the
two positions of the head.
Fig.2.3 The position of the neck ring determines the angle of the head
For calibration, only the pinnae have to be removed (see section 2.3.1). To replace a
preamplifier cable, for example to use a longer one, you have to separate the head
from the torso (see section 2.3.3). The microphones and preamplifiers should only be
removed when the simulator is being serviced (see Chapter 4).
The simulator comes with an absorptive cover for the torso (see Fig.2.3). This ad-
justs reflections and diffraction from the upper part of the torso to optimize the
directivity of the entire simulator.
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Chapter 2 —Getting Started
Assembly and Dismantling
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
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2.3 Assembly and Dismantling
2.3.1 Attaching and Removing the Silicone Pinna
The pinna simulator is attached to the head by four small lugs which fit into slots in
the square opening on the side of the head.
Take a firm hold of the ear-flap (Fig.2.4), and push (or pull) it forward towards the
front of the ear. The two back lugs should come out. You can then pull the ear out of
the two front slots.
Fig.2.4 Removing the pinna ear simulator
Once you have removed the pinna simulators from the head, you can calibrate the
microphones (see Chapter 3).
2.3.2 Adjusting the Neck Ring
The black neck ring which sits between the head and the torso is used to change the
angle at which the head rests on the torso. Change the angle as follows:
1. Remove the two square rubber inserts from the bottom of the torso by pulling
them out. This loosens the preamplifier cables
2. Turn the head 90°to the side and lift off as shown in Fig.2.5
3. Rotate the neck ring 180°to its new position. With the thin side of the ring placed
at the front of the torso, the head is lowered to a resting position. When the
thicker side of the ring is at the front of the torso, the head is upright
4. Place the head back on the torso (90°from forward) and turn it so it once again
is faces forwards (aligned with the mark on the neck ring, Fig.2.7)
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Chapter 2 —Getting Started
Assembly and Dismantling
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
Brüel & Kjær
12
Fig.2.5 Separating the head from the torso
2.3.3 Changing Preamplifier Cables
Use the procedure given in section 2.3.2 to loosen the head and gain access to the
preamplifier connectors.
2.3.4 Mounting and Mounting Holes
There are a number of threaded mounting holes on the simulator.
The holes on the sides of the torso are provided to allow you to attach the accompa-
nying handle UA 1052 (see Fig.2.6) or to fix the simulator in Positioning Frame
UA 1324.
The holes at the top of the head and on the chest are for attaching optional equip-
ment, for example clothing (hat) or other fixtures.
2.3.5 Scales and Mounting Guides
There are scaling and mounting guides on the top of the head, as well as around the
ear cavities and on the side of the neck ring (see Fig.2.7).
The scales at the top of the head are for determining the angle at which to locate the
sound source for testing, while the mounting guides around the ear cavities are used
to adjust the placement of headphones in a calibration procedure. The mark on the
neck ring is to ensure that the head faces forwards.
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Chapter 2 —Getting Started
Assembly and Dismantling
Sound Quality Head and Torso Simulator Type 4100, 4100 D
User Manual
BE 1391 –13 13
Fig.2.6 The handle UA 1052 fitted to the torso. The bottom end-piece cover has not been fitted so that
the screw and the end-piece can be seen
Fig.2.7 Scaling and mounting guides (left), headphone and head mounting guides (right)
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Sound Quality Head and Torso Simulator Type 4100, 4100 D
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Chapter 3
Calibration and Setup
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