Infield Gehoer 16-S GB - infield-safety

Service and delivery
Package of INFIELD hearing protection
Contact
Delivery
INFIELD hearing protection comes with easy to follow instructions. We
also offer on-site consultation through our sales force.
Service
We offer comprehensive consultation and aftercare. Please contact us
directly for general information and individual queries.
Warranty
INFIELD hearing protection products are of high quality and can last
many years with the appropriate care. We offer a 2 year warranty on
fit and protection.
INFIELD SAFETY (UK) Ltd.
Unit B
Brocks Business Centre
Homefield Road
Haverhill
Suffolk
CB9 8QP
Tel: 01440 705286
Fax: 01440 705557
Email: info@infield-safety.co.uk
www.infield-safety.co.uk
INFIELD SAFETY is a member of the Signet Armorlite Group.
16
© 07.12.110.1
Blindness separates us from things.
Deafness separates us from people.
Immanuel Kant

Table of contents
Subject Page
Introduction 3
The human ear 4
Hearing – how does it work? 5
What is loud? 5-6
Protective capacity 6
Hearing loss caused by noise 7
Legislation and directives 8
Frequency analysis 8
Frequency analysis jargon 9
Customised hearing protection made by INFIELD 10
Advantages of INFIELD’s ear plugs 10
Material 10
Moulding and manufacture 11
Compact Filter 12
Clear Sound Filter 13
Phonor Pro Filter 14
Seal Integrity Test 15
(Air-) Leakage Test 15
Acoustic Test 15
Service and delivery 16
Contact 16
2
Hearing damage caused by noise is irreversible
We’re asleep. Our entire body is at rest. The muscles, the eyes, the ears –
or so you think! Our ears never sleep! Or how could you explain that we
are awoken by sounds? Be it an intruder alarm, a smoke detector, a crying
baby, a coughing partner or the alarm clock: It wakes us up. This proves that
our ears are wide awake while we’re asleep – all the time.
Most people are unaware of the health problems that noise can cause.
Especially young people expose their ears to high levels of noise by going
to rock concerts and night clubs or using MP-3 players with earphones. In
the medical profession recognises 85dB (Decibel) as the threshold for
hearing damage, 120 -130dB as the pain barrier – this equates to a jet
plane at take-off at 100m distance. The background noise in houses is
typically 40-50dB, in offices 65dB. Traffic noise can easily amount to
85dB, rock concerts and night clubs at 110dB are often louder than
jackhammers giving off 100dB. An increase of 3dB doubles the charge on
the ears.
In the workplace the noise level at which hearing protection must be worn
is legislated. But often the provided equipment isn’t worn by workers - but
why? One reason is that some hearing protection lacks comfort and
practicality, because it makes communication almost impossible. As a
consequence the user feels isolated. Some users also complain about
headaches, contact allergies or sweating under the equipment.
Customised hearing protection by INFIELD Safety is comfortable and reduces
the noise level without acoustic isolation of the user.
In this brochure you will discover how the safety experts at INFIELD have
achieved the production of quality hearing protection that provides high user
comfort also.
3
Introduction
Reasons for rejection of hearing protection
INFIELD earplugs

Anatomy of the human ear
Diagram of the ear
1. Outer ear
2. Ear canal
3. Eardrum
4. Hammer
5. Anvil
6. Stirrup
7. Oval window
8. Semicircular canals
9. Auditory nerve
10. Cochlea
11. Eustachian tube
12. Round window
13. Tympanic cavity
Outer ear
The outer ear is made up of the visible portion called the pinna and the ear
canal. The human pinna’s functions are of no great importance, whilst
animals can move and turn their ears to locate sounds.
Middle ear
The middle ear consists of eardrum, tympanic cavity and Eustachian tube.
Inner ear
The inner ear is made up of the organ of Corti and the cochlea.
Ear canal
The ear canal links the outer ear and the eardrum. It is approximately 3-4cm
in depth and 0.5-1cm in diameter. It is completely covered with skin. The
outermost part of the ear canal near the pinna is supported by cartilage, the
inner part by bone. In the section made up of cartilage sebaceous glands
secrete the yellow cerumen which is expelled by tiny hairs.
Eardrum
Between the ear canal and the tympanic cavity lies the eardrum. This membrane
is approximately 1cm in diameter and 0.1mm thick. On the inside of
the eardrum is a mucous membrane; from the outside it looks grey and shiny.
Tympanic cavity
In the tympanic cavity there are the three ear bones or ossicles: hammer,
anvil and stirrup as well as the semicircular canals of the vestibular
apparatus.
Hammer, anvil and stirrup
The hammer, anvil and stirrup are three tiny bones that are connected to
each other. They directly couple and amplify sound energy from the eardrum
to the inner ear.
Oval window
Sound waves travel via this membrane from the ossicles to the inner ear. The
inner ear is located in the cochlea, well protected by the petrous portion of
the temporal bone (‘pyramid’).
Round Window
The round window is positioned adjacent to the oval window and is the end
point of the scala tympani.
Eustachian tube
The Eustachian tube links the tympanic cavity with the pharynx. Its main
function is pressure equalisation in the ear.
Cochlea
The cochlea has three ducts called scalae: the scala vestibuli and the scala
tympani, which both contain perilymph. Between these two is the scala
media filled with endolymph which contains the organ of Corti. The word
cochlea is the latin word for snail and comes from the shape of the organ.
Organ of Corti
The organ of Corti is the essential part of our hearing. It is located in the
cochlea and contains 25,000 hair cells, each equipped with 100 hairs
called stereocilia. These hairs are the sensory receptors of the auditory
system and pass on information from sound waves via the auditory nerve to
the brain.
4 5
To be precise, the human ear doesn’t process sounds, but sound waves that
resonate with the eardrum. The resonance is amplified by the ossicles in the
tympanic cavity and reaches the inner ear through the oval window, where
the actual hearing process begins.
A very important factor in the hearing process is the frequency of sound. The
unit of frequency is Hertz (Hz) and is a measure of the number of sound
waves per second.
The amplification of sounds by the ossicles depends on frequency. The best
amplification of sounds is achieved in the range of the human voice, i.e. between
1000 and 2000 Hz.
When a sound wave reaches the oval window via the previously mentioned
pathway, it is passed on via the perilymph inside the scala vestibuli to
trigger the basilar membrane. Depending on the frequency, sensory hairs in
different locations on the organ of Corti are triggered. An analogy would be
waves breaking at specific points on the beach, depending on their size.
This way we can distinguish between high and low pitches. From the
stereocilia the sound wave travels on towards and resonates with Reissner’s
membrane. This resonance then triggers receptor cells that send an electric
impulse along the auditory nerve to the brain. Here the sound is recognised
and defined e.g. as a note or a word. The ear responds 7 times faster than
the eye. If we could see as fast as we can hear, we would see every single
frame in TV broadcasts instead of fluid movements.
A sound is not only defined by its frequency but also by its volume. This is
measured in decibel (dB). The table below lists typical everyday sounds and
the noise level they cause.
The human pain barrier for sounds is about 120dB, i.e. at volumes above
120dB we perceive the sound as a physical pain in our ears.
If we have to raise our voice in a conversation at a distance of 1m, the
background noise level is about 80dB or more. It is not advisable to expose
the ears to such noise levels for prolonged periods without hearing
protection.
Hearing – how does it work?
Cochlea
1. Stirrup
2. Oval window
3. Helicotrema
4. Scala vestibule
5. Organ of Corti
6. Scala tympani
7. Round window
Diagram of the cochlea
1. Scala vestibule
2. Organ of Corti
3. Scala tympani
4. Auditory nerve
What is loud?
Examples of noise levels in Decibel

What is loud?
Logarithmic increase of volume (dB) in comparison to
weight (kg)
Protective capacity
Decrease of protective capacity
Volume is often underestimated because the decibel scale is not linear but
logarithmic. This means that for every 10dB the intensity rises by 10-fold. To
illustrate the difference, weights can be used as an example.
Going from 60dB to 70dB is particularly dramatic: 10dB is the same
proportional difference as there is between the weight of an average adult
and a family car.
When going 10dB higher the analogy in weight is a heavy goods vehicle.
The duration of exposure is an important factor in hearing loss. The human
ear has its own protective capacity, similar to the role of melanin in the skin
to protect it from UV radiation. Hence we can expose our ears to 80dB for
8 hours without any lasting damage. An increase of 3dB to 83dB halves
this exposure time, i.e. 4 hours are safe. Please refer to the diagram for
further protective capacity times.
If you are exposed to noise levels of 80dB or above, hearing protection
becomes a necessity to prevent lasting damage to your ears.
6 7
Continuous exposure to noise causes hearing loss that is irreversible in 95%
of all cases.
Very often our bodies show symptoms that are not obviously linked with
noise, like insomnia, poor concentration and cardiovascular disease. If you
suffer from any of these complaints, it is advisable that your surroundings are
analysed for noise. In case that sources of dangerous noise levels have been
identified and cannot be eliminated, hearing protection must be worn. Find
more conditions associated with noise damage in the following paragraphs.
Conductive hearing loss
Damage to the ossicles (hammer, anvil and stirrup) renders them unable to
amplify sounds adequately. This results in a hearing loss of approximately
20dB.
Sensorineural hearing loss
Loud noises destroy the hair cells in the organ of Corti and can cause partial
or complete loss of hearing.
Tinnitus
Around 3 Million people suffer from tinnitus (Latin for ‚ringing’). This constant
noise in the ears is mostly described as a whistling sound, but can also take
the form of a buzzing, whooshing or rattling. It can not be measured but is
proven to lead to psychological problems and even suicide. There are many
attempts for therapy but no guarantees for a successful cure. Tinnitus is not
only caused by noise but also by stress, middle ear infection, decreased
blood flow to the inner ear or some medications.
Vertigo
Because the vestibular system located in the inner ear is also responsible for
the sense of balance, damage to the ear can also cause vertigo and
dizziness.
Often these symptoms are ignored, because they aren’t very obvious at first
and they have a very slow progression. Protect yourself, your employees and
your relatives with individually fitted hearing protection.
Hearing loss caused by noise

Legislation and directives
Frequency analysis
First of all, the term ’noise’ needs to be defined. Legislation describes it as
‘any type of sound that disturbs, bothers or damages the health of people,
i.e. all sounds that compromise physical, mental and social well-being’.
According to a new EU guideline (2006) the following applies:
- at 80dB or above, hearing protection must be provided
- at 85dB or above, hearing protection must be worn
Hearing protection on sale in Europe needs a CE-mark, i.e. comply with the
standards of the European Committee of Standardisation (CEN). Within
these EU-standards, hearing protection falls into the category of ‘personal
protective wear’ and is divided into three sub-categories:
• EN 352-1: ear-muffs
•EN 352-2: ear-plugs
• EN 352-3: ear-muffs attached to safety helmets
This has been replaced in 2003 by a new series of EU-directives:
•EN 13819-1: physical test methods for hearing protection
•EN 13819-2: acoustic test methods for hearing protection
• The old 352-series is limited to the specific demands that are set by
delivery conditions and guidelines
For optimum protection detailed knowledge of the work environment of the
end user is needed. The noise level in manufacture is not only made up of
the machine in use but also many other background noises with different
frequencies. Specialists have fixed 1000Hz as the standard frequency; this
is the lower range of the human voice. A professional frequency analysis as
it is carried out by INFIELD always refers to 1000Hz as well as six other
frequencies. Three of these frequencies are higher in octave steps; three are
lower in octave steps. The fixed frequencies are 125, 250, 500, 1000,
2000, 4000 and 8000Hz. Please note that a comprehensive frequency
analysis is a sign of professionalism and quality of service.
In the frequency based tables for noise reduction you find a lot of numbers
we would like to explain to you. Now that you are familiar with how these
frequencies have been chosen, we’ll explain more about the individual
numbers.
8 9
The M f - value, measured in dB, determines the mean attenuation of a
frequency. For example 25dB at 500Hz means a noise reduction of 25dB
at the frequency of 500Hz.
The APV (Assumed Protection Value) is measured in dB. The CE-mark is only
issued for hearing protection if this value is above legislated level. The APV
should not be less than declared for 84% of end users.
The S f - value (in dB) is an assumed standard deviation that contributes
towards the determination of the APV.
The SNR - value is the mean attenuation for the complete analysed spectrum
of frequencies, i.e. from 125-8000Hz.
The H/M/L - values are the mean attenuation in the respective areas of
frequencies.
H = High frequency (2000-8000Hz)
M=Medium frequency (500-2000Hz)
L = Low frequency (125-500Hz)
The graphs illustrate the attenuation that is achieved by the individual
acoustic filters. Customised hearing protection provides attenuation that is
evenly balanced across the relevant spectrum of frequencies in contrast to
standard hearing protection.
Frequency analysis jargon
Legislated APVs for the CE-mark
Attenuation table in original size: pages 12-14

Customised hearing protection made by INFIELD
Advantages of INFIELD’s ear plugs
Material
We offer three types of ear plugs to furnish a range of requirements:
• Compact
•ClearSound
• Phonor® Pro
The Compact FlexComfort and ClearSound both come with a complimentary
set of accessories:
•Cord with clip
•Cleaning stick and Otoferm cream
• Case
The Phonor® Pro comes with complimentary:
•Case and cleaning stick
Cleaning spray and tissues can be ordered as accessories.
Special models
All models can be fitted with a tiny metal ball (detection ball). These
specialised models are mainly of interest to the food and chemical industries.
•Customised for perfect fit
• Optimum protection
•Communication is retained
• Filters are individually adjusted to the environment
•Important sounds and signals can still be heard
•Ideal comfort, hardly noticeable
•High user acceptance
• Easy to wear with safety helmets
• Almost invisible
• Easy to use
• Easy to clean
The standard material for all our models is silicone, which provides good
mechanical and chemical resistance combined with a long life span. The
soft, flexible material causes no pressure points in the ear canal, even with
prolonged wearing. The basic standard issue of the ear plugs is transparent
silicone, but they can also be produced from a harder acrylate plastic and
in a range of signal colours like red, blue or yellow.
10 11
The ear plug is custom moulded to each user and consists of the silicone plug
and the acoustic filter itself.
Before fitting the ear plug, a medical examination has to be carried out to
assess that it is safe to inject the moulding putty into the ear canal. During
this examination, excess cerumen (earwax) or cerumen plugs should be syringed
from the ear canal.
The moulding is performed according to current best practice for the fitting
of hearing aids. The moulding material is a pliable two-component putty
based on silicone. This is injected into the ear canal without any noticeable
pressure. The moulding process is normally not uncomfortable. The result is
a perfect copy of the ear canal and part of the pinna.
In the next production step, this mould is then used to form the final earpiece.
It fits perfectly into the ear canal and provides a tight fit. Then a hole is
drilled into the part that inserts into the ear canal. Now the appropriate
acoustic filter is fitted, specifically tuned to your requirements for noise reduction.
Compared to other systems, custom made hearing protection has many
advantages. It is anatomically fitted to each user’s ear canal, therefore can
neither slip nor cause pressure points and the protection is consistent throughout
usage. It doesn’t close up the ear canal completely, but is ventilated
through the acoustic filter, which also allows pressure equalisation. In this
way user comfort is maximised.
The large range of acoustic filters allows for a multitude of noise environments,
eliminating under- or over-protection.
Moulding and manufacture
Moulding process with the injector gun
Moulding the gypsum cast
Refining the first mould
Drilling the hole for the acoustic filter

Compact Filter
Earplug with Compact Filter
Broad band filter
The 4 filters of choice MM 12, MM 22, MM 02 and ML 01 find their
use in different situations to filter specific frequencies. They are unique in
their broad band characteristics. The filters MM02 und ML01 are used
at low frequencies (e.g. turbine manufacture, sheet metal production).
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RC 19/18/17/15/13* - Range with reduced attenuation complying
with the new EU noise directive. These broad spectrum filters have very
linear attenuation properties and show no peaks in the spectrum of the
human voice. These properties assure that the user doesn’t feel isolated
and that voices, alarms and signals relevant to health and safety can still
be heard. Main fields of use are in railway and monitoring of machine
noises.
* RC13: at 125Hz and 250Hz, the APV84 is with 0.9 and 1.3
respectively lower than the minimum required attenuation with regards to
EN 352-2, i.e. the standard CE does not apply.
Clear Sound Filter
Ear plug with Clear Sound filter
Clear Sound filter

Phonor® Pro Filter
Phonor® Pro Filter
Tubular filter
•Customised hearing protection, 100% made in Germany
•2 acoustic filters with different characteristics
• Choice of 2 materials: acrylate and FlexComfort
•Available with or without cord
•Detector ball available for easy tracking when lost
• Filter is protected from dirt
• Field of use in industry
Pro M and Pro H – Both these filters are simple tubular filters that provide
good protection at medium and high frequencies. They are not suited for
use at low frequencies.
The Pro filters meet the simpler requirements in industrial uses.
There are two main methods to test the tight fit of customised hearing
protection: the (air) leakage test and the acoustic test. Please note that the
total attenuation is mainly a measure of the fit of the ear plug rather than the
actual function of the acoustic filter. The main difference is that seal integrity
tests are carried out for each ear (monaural) whilst the total attenuation is
measured for both ears at the same time (binaural).
If you require tests on your ear plug to confirm the high standard of our
products, INFIELD can carry these out for you at your request.
Procedure:
A small pump that has been developed specifically for this task increases the
pressure between the ear plug and the eardrum. The ear plug has a tight fit,
if the pressure doesn’t decrease.
Advantages:
• Quick and simple method
•No special facilities necessary
• Objective - does not rely on the test persons’ perception
Disadvantages:
• The cable connector can temporarily alter the fit of the ear plug and have
a negative influence on the test results
• The test environment should not be too loud as this can alter the test results
• Can not be applied to all ear plugs
The test is carried out with a micro processor, which is fitted with two microphones.
One of the microphones is connected to the ear plug and measures
the noise level behind the hearing protection (in front of the eardrum). The
other one measures the noise level in front of the hearing protection. After
applying the ear plug to the ear, a low frequency test sound is generated.
The difference in noise levels is the total attenuation.
Advantages:
• Precise measure of attenuation in dB
• Quick and simple method
• Objective - does not rely on the test persons’ perception
•No special facilities necessary
14 15
Disadvantages:
• The test environment should not be too loud as this can alter the test results
Seal integrity test
(Air-) Leakage test
(Air-) Leakage test
Acoustic test
Acoustic test