Download What is Noise?

The Effects of Noise
on Hearing
How to Protect your Ears from
Damage by Loud Sounds
Carol Rousseau, M.A., CCC-A
Clinical Audiologist
Rochester Hearing and Speech Center
Rochester, New York
5 March 2009
Goals for Presentation
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What is Noise?
How we hear -- anatomy and
physiology of the ear
How noise effects the ear
Discuss and demonstrate various types
of Hearing Protection Devices (HPD)
What is Noise?
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Subjective
Unpleasant or unwanted sound
It is a by-product of many industrial
processes
What is Noise?
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Exposure to high levels of noise can
cause hearing loss as well as other
health related issues
Anatomy of the Ear
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Conductive
– Outer Ear
– Middle Ear
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Sensorineural
– Inner Ear
– Auditory Nerve
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Central
– Brain
Anatomy and Physics
of the Ear
What is Noise-Induced
Hearing Loss?
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Caused by damage to the cochlea due
to the over stimulation of the inner ear
structures
– Mechanical damage
– Chemical damage
What is Noise-Induced
Hearing Loss?
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Damage can occur in two ways
– Sudden intense noise that can cause
an acoustic trauma
– Long-term exposure to intense noise
What is Noise-Induced
Hearing Loss?
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Extent of damage depends on the
intensity of noise and the duration of
the exposure
– Noise louder than 85 db can cause
damage
– Risk of hearing loss from noise doubles
with each 3 dB increase in sound level
Decibel Exposure Time
Guidelines
Continuous dB
85 dB
88 dB
91 dB
94 dB
97 dB
100 dB
103 dB
106 dB
109 dB
112 dB
115 dB
Permissible Exposure Time
8 Hours
4 Hours
2 Hours
1 Hour
30 Minutes
15 Minutes
7.5 Minutes
3.75 Minutes
1.875 Minutes
.9375 Minutes
.46875 Minutes
Audiogram
Noise-Induced Hearing Loss
Healthy and Damaged
Hair Cells
Physiologic Effects on the
Cochlea
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Loss of hearing sensitivity
– Especially in the High Frequencies
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Loss of clarity
Decreased sound localization
Reduced tolerance to loud sounds
Other Physiological
Effects
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Tinnitus
Cardiovascular
Mental Health
Noise Combined with
Chemical Agents
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Some substances may be more
dangerous when combined with noise
exposure
– Aspirin
– Some antibiotics and chemotherapy drugs
– Industrial chemicals such as lead,
styrene, carbon dioxide, and carbon
disulfide
Damage can either be
Temporary or Permanent
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Temporary Threshold Shift (TTS) it a temporary
elevation of the hearing threshold at one or more
frequencies
– Short-term exposure to noise
– Comes back after a period of rest
Permanent Threshold Shift (PTS) is a permanent
elevation caused by damage to the hair cells, which
can not be regenerated once they are injured
– Prolonged exposure to high noise levels over a
period of time
– Gradually causes permanent damage
Hearing Protection
Devices
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Occupational
Recreational
Occupations Who May
Need HPD
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Industrial Workers
Construction
Military
Musicians and Other Entertainment Professionals
Farmers
Day Care Workers
Dentists
Pediatricians
Nurses
Recreational Activities
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Music
– Stereo and Personal Listening Devices (iPods)
– Concerts
– Performing
Hunting and Target Shooting
Motorcycling
Drag Races and NASCAR
Snowmobiling
Woodwork
Lawnwork
Volume Settings and dB(A) Readings of a
Number of Popular Personal Listening Devices
Player
Full Vol 3/4 Vol
1/2 Vol
1/4 Vol
Low
Apple iPOD (15 GB)
120-125
107-111
98-101
80-83
68-72
Creative Zen Nano
Plus
114/118
105-109
85-92
77-82
67-75
iRiver T10
108-115
115-122
98-104
105-112
85-94
98-106
78-83
88-92
55-62
70-79
Dell Latitude D610
Laptop
112-114
108-114
102-108
85-96
74-77
115-120
112-118
112-115
100-105
90-94
87-99
69-72
70-76
45-50
60-66
Sony Walkman
MP3/ATRAC3plus
Bratz-Liptunes MP3
Disney Mix Stick
Types of HPD
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Ear Plugs
Ear Filters
Ear Muffs
Semi-Aural Protectors
Custom Ear Molds
In-the-Ear Monitors
Ear Plugs
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Generally made of soft polyurethane
or silicone foam, wax
One Size Fits All
Inserted into Ear Canal
Disposable
Attenuates 20-40 dB
Reduces high frequencies more than
low, giving a muffled sound
Non-custom Foam Ear
Plugs
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29db of attenuation
Pre-molded Ear Plugs
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Made of vinyl,
silicone or rubber
Come in different
sizes for fitting
Re-usable
Ear Seals
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Soft flanged ear
seals
Detachable cord
Ear Filters
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Attenuates sound more evenly through
baffles or moving diaphragms
One size fits all
Non-custom Musicians’
Earplugs
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ER-20
Attenuates sound
more evenly
through baffles or
moving diaphragms
No custom mold
needed
Ear Muffs
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Circum-aural
protectors
Adjustable
Semi-Aural Protectors
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Ear plugs tips
connected to a
headband
Usually one size fits
all
Can be taken on/off
quickly
Attenuation less
than that of other
HPDs
Custom-made
Ear Molds
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General purpose
solid ear plugs
Custom molded for
the individual
Reusable
Industrial Ear Plugs
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Custom molded ear
plugs
Attenuates
approximately 29
dB
Hunters Ear Plugs
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Pressure valve for
occasional high
impact noise
Allows normal
hearing until a gun
shot activates the
valve
Motorcycle Ear Plug
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Canal style
Comfort while
wearing under a
helmet
Also for sleeping
Swim Plugs
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For swimmers
Kid with PE tubes
Exposure Ear Plugs
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Keeps out the
environment but
allows for
communication
For surfers, dude
Custom Musician Ear
Plugs
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a special filter allows the
listener to hear music at a safe
level without sacrificing sound
quality
Instead of cutting out the high
frequencies, musician's plugs
attenuate all the frequencies
evenly in relation to your
hearing.
Custom plugs come in ER-9 ,
ER-15 or ER-25 filters
An audiologist or other
hearing health professional
takes impressions of the ear
canal.
In-the-Ear Monitors
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Provide up to 25 dB
of attenuation from
ambient noise
Earmolds for Westone UM1
and UM 2 earphones
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Requires custom
earmolds to be
taken by an
Audiologist
Thank you very much
You’ve been a great audience!