Custom Noise & Hearing
Protectors
The information here is not
intended to replace professional advice or care.
ACA is recognized
as a leading provider of high-quality hearing health care
services. ACA is unique in its organizational scope of practice by
choosing to provide all aspects of audiological care, combining
comprehensive diagnostic services with our rehabilitative services.
Our staff
of licensed, nationally certified audiologists also provides various services
to individuals exposed to high levels of sound either at work or in recreational
activities, including baseline hearing
evaluations, sound-level measurements for noise
environments, earmold impressions for hearing protection devices, custom
high-fidelity ear plugs (ER-9/15/20/25) and dispensing of a wide variety
of hearing aid
systems.
Custom Hearing Protection
Advantages of Custom Hearing Protection
Custom-made hearing protection inserts are manufactured to
fit individual ears, providing repeatable performance, consistent protection
and increased comfort for longer periods of time.
They are available in a variety of medical-grade silicone
and vinyl materials to reduce irritation of sensitive ears.
Custom products are designed for several years of reliable
use. Long life results in low cost per individual per day.
-
Custom Hearing Protection Considerations
-
For maximum protection, "full-shell" style protectors are
recommended.
-
Filtered sound plugs provide less noise attenuation than
solid plugs.
-
Sound attenuator ear plugs and ER-9/15/25 musicians' plugs
may not be suitable for conditions of higher noise levels or increased
exposure times.
-
Custom hearing protectors are designed to fit in the ear
in only one way. Right/left identification dots or designators are
available on all custom products.
-
If plugs are used in combination with ear muffs, use hearing
protectors with recessed removal handles or sound plugs without removal
handles. Removal handles may disturb the seal between the skin and the
muffs.
-
Care and Maintenance of Custom Hearing Protection Products
-
Custom hearing protectors should be cleaned of cerumen (ear
wax) and dirt after each use.
-
Rubbing alcohol and harsh detergents can harden and yellow
soft ear plug materials. Use a damp cloth for longer life.
-
Hearing protectors and sound plugs can be cleaned with water
on a damp cloth.
-
Sound or ear plugs with a non-removable filter should be
wiped clean with a dry cloth.
ER-9/15/25 musicians' plugs are designed with a detachable
attenuator filter button. Remove the button prior to cleaning with
water or a damp cloth. Allow to dry before replacing the button.
Problems with Conventional
Earplugs
-
Problem 1. Existing
earplugs attenuate much more than necessary for much of the noise in industry
and the environment.
-
Problem 2. Regardless
of their exact construction, existing earplugs produce 10- to 20-dB of
high-frequency attenuation, resulting in their rejection because people
can't hear speech clearly.
-
Problem 3. Existing
earplugs make the wearer's own voice sound hollow (known as the occlusion
effect).
-
Problem 4. Many
people risk their hearing by either wearing earplugs loosely or by wearing
no protection at all so they can hear voices, machinery or music more clearly.
Theory and Design of a Flat-Response
"High-Fidelity" Earplug
The ER-series
of custom-fit hearing protectors provide equal attenuation at all frequencies,
allowing the wearer to hear sound naturally and clearly, but at a lower,
SAFER
sound
level. The ER-series of earplugs alleviate complaints assocated with
conventional earplugs, such as the occlusion effect, "dullness" of sound
and over-attenuation of volume. Four levels of attenuation are available:
-
ER-9 provides approximately 9-dB of attenuation
-
ER-15 provides approximately 15-dB of attenuation
-
ER-20 provides approximately 20-dB of attenuation
-
ER-25 provides approximately 25-dB of attenuation
|
A flat-response, high-fidelity
earplug must have a frequency response that follows the shape of the natural
frequency response of the open ear but at a reduced level. The ER-9,
ER-15 and ER-25 earplugs use a diaphragm, similar to a passive speaker
cone, to achieve the desired response curve. The ER-20 is a stock
(non-custom) earplug that uses a tuned resonator and acoustic resistor
to achieve a high-fidelity response. To reduce the occlusion effect--
in which the wearer's own voice sounds hollow and unpleasant-- a seal of
the plug in the second bend of the ear canal (deep in the ear canal) is
necessary.
In general, ER-15 protectors are designed for environments where the A-weighted
sound pressure level is 105 dB or lower. ER-25 protectors are designed
for use in environments above 105 dB and below 120 dB. The attenuation
shown in the above graph is for an average ear. When put properly
in place, ER-15 protectors will provide a minimum of 10 dB of attenuation,
ER-20 protectors will provide a minimum of 15 dB of attenuation
and ER-25 protectors will provide a minimum of 20 dB of attenuation. |
 The
ER-series of earplugs is designed for protection, comfort, and high-fidelity. |
How Much Noise is Too Much?
|
Noise Source
|
Decibels
|
|
Rocket Launching Pad
|
180
|
|
Jet Plane
|
140
|
|
Shotgun Blast
|
140
|
|
Riveting Steel Tank
|
130
|
|
Automobile Horn
|
120
|
|
Sandblasting
|
112
|
|
Woodworking Shop
|
100
|
|
Punch Press
|
100
|
|
Pneumatic Drill
|
100
|
|
Boiler Shop
|
100
|
|
Hydraulic Press
|
100
|
|
Can Manufacturing Plant
|
100
|
|
Subway
|
90
|
|
Average Factory
|
80-90
|
|
Noisy Restaurant
|
80
|
|
Office Calculator
|
80
|
|
Busy Traffic
|
75
|
|
Conversational Speech
|
66
|
|
Average Home
|
50
|
|
Quiet Office
|
40
|
|
Whispered Speech
|
30
|
Noises over 140 dB cause PAIN.
Exposure to noises over 90 dB harms hearing.
Want more information
about
the adverse effects of noise
on your ears?
For more information about noise and hearing loss, click
here!
For more information about noise-induced tinnitus, click
here!
Safe Exposure Levels
Noise induced hearing loss is a function of three factors:
-
Exposure time
-
Average noise level
-
Peak level of very loud sounds
Some people seem
to be more susceptible to hearing loss than others, so that protection
on the basis of an average time and average sound level exposure will protect
only the "average" person. The table below provides allowable safe
exposure for sound using both the conservative "equal energy" approach
and the U.S. Occupational Safety and Health Administration (OSHA) standard.
This table is based on a conservative assumption of the amount of attenuation
provided by various custom high-fidelity ear protectors. In other
words, in most ears:
-
ER-15 protectors will provide a minimum of 10 dB of
attenuation
-
ER-20 protectors will provide a minimum of 15 dB of
attenuation
-
ER-25 protectors will provide a minimum of 20 dB of
attenuation
Average Safe Hours
per Day
Noise Level
in dB
|
No
Protection
|
10-dB
Protection
|
15-dB
Protection
|
20-dB
Protection
|
|
|
|
EE
|
OSHA
|
EE
|
OSHA
|
EE
|
OSHA
|
EE
|
OSHA
|
|
85
|
|
8
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
88
|
|
4
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
90
|
|
---
|
8
|
---
|
---
|
---
|
---
|
---
|
---
|
|
94
|
|
1
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
95
|
|
---
|
4
|
8
|
---
|
---
|
---
|
---
|
---
|
|
97
|
|
0.50
|
---
|
---
|
---
|
---
|
---
|
---
|
---
|
|
100
|
|
0.25
|
2
|
2.50
|
8
|
8
|
---
|
---
|
---
|
|
105
|
|
0
|
1
|
0.75
|
4
|
2.50
|
8
|
8
|
---
|
|
110
|
|
0
|
0.50
|
0.25
|
2
|
0.75
|
4
|
2.50
|
8
|
|
115
|
|
0
|
0.25
|
0
|
1
|
0.25
|
2
|
0.75
|
4
|
|
120
|
|
0
|
0
|
0
|
0.50
|
0
|
1
|
0.25
|
2
|
|
125
|
|
0
|
0
|
0
|
0
|
0
|
0.50
|
0
|
1
|
|
Recreational Plugs for Specific
Applications
|
Music
Industry
|
Musician ear plugs
In-ear earphone monitors
|
|
Aircraft
|
Headsets with tube and bar
|
|
Communications
|
Security earmolds
Custom in-ear monitors
|
|
Hunters / Shooters
|
Solid ear plugs
"Sonic valve" ear plugs
Sound Scopes
|
|
Swimmers
|
Floatable ear plugs
|
|
Motor Sports
|
Solid ear plugs
Filtered ear plugs
|
|
Medical
|
Anesthesiology ear molds
|
|
Construction / Industry
|
Sold ear plugs
Filtered ear plugs
Sonic valve ear plugs
Ear muffs
|
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In general, ER-15 protectors are designed for environments where the A-weighted
sound pressure level is 105 dB or lower. ER-25 protectors are designed
for use in environments above 105 dB and below 120 dB. The attenuation
shown in the above graph is for an average ear. When put properly
in place, ER-15 protectors will provide a minimum of 10 dB of attenuation,
ER-20 protectors will provide a minimum of 15 dB of attenuation
and ER-25 protectors will provide a minimum of 20 dB of attenuation.