Transcript CSD 3000 DEAFNESS IN SOCIETY

CSD 2230
HUMAN COMMUNICATION
DISORDERS
Topic 5
Hearing Disorders and Hearing Loss
Introduction to Sound
Types of Hearing Loss
Sound System
Source

Any vibrating object
Medium

Any gas, liquid or solid
Receiver

anything designed to
detect the vibrations
within the medium
originating from the
source
A Common Sound System
Illustration of the
distribution of
molecules
surrounding a
source in an instant
in time
Condensation and Rarefaction
Bands of condensation
and rarefaction
emanating from a
sound source
Propagation of a Disturbance
Through a Medium
Notice that as time goes on, molecules farther from the source
become affected by the disturbance.
Important Physical
Characteristics of Sound
Frequency



Rate of pressure
change as a
function of time
Measured as
cycles/sec or Hertz
The primary
determiner of pitch
Intensity



Magnitude of the
pressure change
Measured as the
decibel (dB)
The primary
determiner of
loudness
Frequency and Intensity
Sounds a and c share
the same frequency
and sounds b and c
share the same
intensity
Loudness and Intensity
Here are some common sounds and their
decibel equivalents
The Hearing System
Basic schematic diagram of the entire auditory
system
Putting It All Together….
Types of Hearing Impairment

A loss of sensitivity

Auditory nervous system pathology
Important Terms
ü



Congenital:
Acquired:
Adventitious:
Time of onset
present at birth
obtained after birth
acquired after birth
Important Terms
ü




Acute:
duration
Chronic:
Sudden:
Gradual:
time
Time Course
sudden onset/short
long duration
rapid onset
changes slowly over
Important Terms
ü




Temporary:
Permanent:
Progressive:
Fluctuating:
time
Time Course
limited duration
irreversible
advancing
changes in degree over
Important Terms
ü
Number of Ears Involved

Unilateral:
Just one

Bilateral:
Both
Hearing Sensitivity Loss
§
“The ear is not as sensitive as normal in
detecting sound”
 Types:
 Conductive
 Sensorineural
 Mixed
Conductive Hearing Loss
n
“Caused by an abnormal reduction or
attenuation of sound as it travels from
the outer ear to the cochlea”
Sensorineural Hearing Loss
n
“Caused by a failure in the cochlea to
transduce the sound from the middle
ear to neural impulses in the VIII
Nerve.”
Sensorineural Hearing Loss
n
Implications include:

A reduction in the sensitivity of the receptor
cells in the cochlea
A reduction in the frequency resolving power
of the cochlea
A reduction in the dynamic range of the
system


Mixed Hearing Loss
n
“A loss with both a conductive and
sensorineural component.”
Types of Hearing Impairment

A loss of sensitivity

Auditory nervous system pathology
Auditory Nervous System Impairment
§


Causes:
Disease
Disordered auditory nervous system
development
Auditory Nervous System Impairment
§


Kinds:
Retrocochlear disorders
Central auditory processing disorders
Auditory Nervous System Impairment
§




Auditory Characteristics:
Reduced ability to understand speech in a
noise background
Problems understanding speech with reduced
redundancy
Problems with localization and lateralization
Problems processing normal or altered
temporal cues
Auditory Pathologies
Outer and middle ear disorders
 Conductive pathologies
Cochlear disorders
 Sensorineural pathologies
Central auditory disorders
 Central auditory pathologies
Outer and Middle Ear Disorders

Structural defects due to embryologic
malformations

Structural changes secondary to
infection or trauma
Outer Ear Disorders

Microtia and atresia
Microtia
“an abnormal
smallness of the
auricle”
n
Atresia
n
“the absence of
an opening of
the external
canal”
Outer Ear Disorders

Microtia and atresia

Impacted cerumen

Perforation of the
tympanic membrane
Outer Ear Disorders

Microtia and atresia

Impacted cerumen

Perforation of the tympanic membrane

Other
Middle Ear Disorders

Otitis Media



Most common
cause of transient
conductive hearing
loss in children
Inflamation of the
middle ear
Caused by
eustachian tube
failure
Ways to Classify Otitis Media
 With or without effusion
 Fluid type
 Serous
 Suppurative
 Mucoid
Ways to Classify Otitis Media
 With or without effusion
 Fluid type
 Duration
 Acute
 Chronic
 Subacute
 Persistent
 Recurrent
Otitis Media Facts





76-95% of all kids will have one episode of OM by age 6
Prevalence is highest during the first two years of life
50% of all kids with one episode before their first birthday will
have 6 or more bouts within two years
Most episodes occur in winter and spring
Risk factors






Cleft palate
Down syndrome
Native Americans
Urban poor
Day care
Secondhand smoke
Middle Ear Disorders


Otitis media
Otosclerosis
Otosclerosis
n
“a bone disorder that
affects the stapes and
the bony labyrinth of the
inner ear. The disease
process is
characterized by
resorption of bone and
new spongy formation
around the stapes and
oval window”
Otosclerosis

Facts:
 Hereditary
 Women are more likely to
develop the disorder
 Usually bilateral
 progressive
Middle Ear Disorders



Otitis media
Otosclerosis
Cholesteatoma
Cholesteatoma
n
“an epithelial pocket
that forms on the
tympanic
membrane. Once
the pocket forms,
the normal shedding
of epithelium results
in growth of the
tumor”
Middle Ear Disorders




Otitis media
Otosclerosis
Cholesteatoma
Other



Physical trauma
Barotrauma
Middle ear tumors

Glomus tumor
Cochlear Disorders

Syndromes and inherited disorders


Syndromic disorders
Nonsyndromal disorders
Syndromes and Inherited Disorders Resulting in
Sensorineural Hearing Loss
Types of Nonsyndromic
Disorders





Dominant
Dominant
progressive
Dominant
progressive with
adult onset
Recessive
hereditary SNHL
X-linked
Cochlear Disorders


Syndromes and inherited disorders
Noise induced hearing loss
Noise Induced Hearing Loss
n
The degree of SNHL depends on
 The intensity of the noise
 The spectral composition of the noise
 The duration of exposure
 Individual susceptibility
OSHA Damage Risk Criteria
Cochlear Disorders




Syndromes and inherited disorders
Noise induced hearing loss
Other trauma
Infections
Infections

Congenital

Cytomegalovirus

HIV

Rubella

Syphilis

Toxoplasmosis
Infections

Acquired

Herpes Zooster Oticus (Chicken Pox)

Mumps

Syphilis
Cochlear Disorders





Syndromes and inherited disorders
Noise induced hearing loss
Other trauma
Infections
Ototoxicity
Ototoxicity

Some antibiotics that are often ototoxic:

Amikacin

Dihydrostreptomycin

Garamycin

Gentamicin

Kanamycin

Neomycin

Netilmicin

Streptomycin

Tobramycin

Viomycin
Ototoxicity

Chemotherapy
 Carboplatin
 Cisplatin

Drugs that cause reversible hearing loss
 Quinine
 Salicylates (aspirin)
 Loop diuretics

Drugs that may be harmful during pregnancy
 Accutane
 Dilantin
 Quinine
 Thalidomide
Cochlear Disorders






Syndromes and inherited disorders
Noise induced hearing loss
Other trauma
Infections
Ototoxicity
Meniere’s Disease
Meniere’s Disease

Symptoms



Tinnitus
Vertigo
Unilateral
sensorineural
hearing loss
Cochlear Disorders







Syndromes and inherited disorders
Noise induced hearing loss
Other trauma
Infections
Ototoxicity
Meniere’s Disease
Presbycusis
Central Auditory Disorders



VIII Nerve tumors
Other diseases of the VIII Nerve
Neural disorders



Brain Stem disorders




Cochlear neuritis
Diabetes mellitus
Infarcts
Gliomas
Multiple sclerosis
Temporal Lobe disorders