2.  Outer Ear
 Middle Ear
 Inner Ear

3.  Pinna (Auricle, Ear)
 External Auditory
Meatus (Ear canal)

4.  Tympanic
Membrane (ear
drum)
 Ossicles
 Middle ear cavity
 Eustachian tube
 Muscles

5.  Thin membrane
separates the outer
ear from middle ear
 Transmits sound from
air to ossicles

6.  Malleus (hammer),
Incus (anvil), &
Stapes (stirrup)
 Vibrate in response to
sound

7.  Equalizes pressure
and allows drainage

8.  Stapedius and Tensor
Tympani
 Retract to loud
sounds to protect
hearing (acoustic
reflex)

9.  Oval window/Round
window
 Cochlea
 8th nerve
 Semicircular canals

11.  Tube divided into 3 fluid-
filled chambers
◦ Scala vestibuli
◦ cochlear duct
◦ scala tympani

12.  Oval window attached to scala vestibuli (at base
of cochlea)
◦ Vibrations at oval window induce pressure waves in
perilymph fluid of scala vestibuli
 Scalas vestibuli and tympani are continuous at
apex
◦ waves in scala vestibuli pass to scala tympani and
displace another membrane, round window (at base of
cochlea)
 Necessary because fluids are incompressible and waves would
not be possible without round window

13.  Low frequencies – travel all the way through scala vestibuli
and back to scala tympani
 As frequencies increase they travel less before passing
directly thru vestibular and basilar membranes to scala
tympani

14.  High frequencies
produce max
stimulation
◦ of Spiral Organ (of
Corti)
◦ closer to base of
cochlea and
◦ lower frequencies
stimulate closer to
apex

15.  Frequency or pitch –
how many waves/sec
a note has
 High frequency – high
number of
frequencies/sec
 Low frequency – low
number of
frequencies/sec

16.  Where sound is
transduced
 Sensory hair cells –
located on basilar
membrane
◦ 1 row of inner cells
extend length of basilar
membrane
◦ Multiple rows of outer
hair cells embedded in
tectorial membrane

17.  Pressure waves moving thru cochlear duct
◦ create shearing forces between basilar and tectorial
membranes
◦ moving and bending stereocilia
◦ causing ion channels to open
◦ depolarizing hair cells
◦ the greater the displacement, the greater the amount of
NT released and action potentials produced

18.  Information from CN VIII goes to medulla, then to inferior
colliculus, then to thalamus, and on to auditory cortex

19.  Neurons in different
regions of cochlea
stimulate neurons in
corresponding areas
of auditory cortex
◦ called tonotopic
organization
◦ where each area of the
cortex represents a
different part of cochlea
◦ and thus a different
pitch

20.  Vestibular (balance)
system
◦ perceive a sense of
balance and perception
in space

21.  Auditory nerve
◦ sound information to
the brain
 Vestibular nerve
◦ position and balance
information to brain

22. APPROACH TO
HEARING LOSS IN A
CHILD

23.  Conductive
 Sensorineural
 Mixed

24. • Sound is not normally
conducted through the
outer or middle ear or
both
• Sound can be picked
up by a normally
sensitive inner
• Often only mild and
temporary
• Caused by any of the
following:
– Ear infections,
otosclerosis, excessive
wax, etc.

25.  Damage of the cochlea
or auditory nerve
 It can be mild,
moderate, severe, or
profound, to the point
of total deafness
 Permanent
 Can be caused by hair
cell damage, noise
exposure, medicines,
genetics, trauma,
illness, etc.

26.  Demonstration

27.  a condition in which a child or adolescent is
unable to detect or distinguish the range of
sounds at the level normally possible by the
human ear
 Hearing loss: results from damage to the outer,
middle, or inner ear, or the auditory nerve
 Auditory processing disorder: hearing loss
resulting from damage to the processing centers
of the brain

28.  Location of damage (outer, middle, inner,
auditory nerve)
 Whether it affects one or both ears
◦ Unilateral or bilateral
 Extent of impact on communication
 Chronicity
◦ Short-term, fluctuating, permanent or progressive
 Timing
◦ Congenital, prelingual, acquired, postlingual

29.  Hearing loss varies in the extent to which it affects
speech, language, and communication
 Affects ability to develop relationships, succeed
academically, and be involved with extracurricular
activities
 Can result in delayed receptive and expressive
speech and language development, can affect any
domain of language

30.  Family needs to respond early, proactively, and
responsively
 Newborn hearing screenings increase likelihood of
early identification
 Parental decisions: communication mode,
communication “orientation” (Deaf vs. deaf)
 Best age for identification and initiation of
intervention: prior to six months

31.  Early Hearing Detection and Intervention (EDHI)
program: 5 to 6 out of every 1000 infants born with
hearing loss
 Eight percent of school-age children have
“educationally significant” hearing loss
◦ Includes cases of acquired hearing loss due to middle
ear infections (35% children experience ongoing middle
ear infections throughout childhood)
◦ Also includes cases of congenital hearing loss due to
pre-, peri-, or post-natal genetic influences, injuries or
illnesses

32.  Classified by either etiology, manifestation and
impact, or severity
A. ETIOLOGY
 For characterizing the cause of the hearing loss:
a. Genetic or environmental cause
b. Age of onset
c. Type of loss

33.  Genetic:
◦ Transmitted from parents to offspring
 autosomal dominant
 autosomal recessive
 Environmental:
◦ Exposure to noise (e.g., ventilator system in NICU)
◦ Sudden exposure to noise or sudden change in air
pressure (barotrauma)

34.  Developmental: present at birth
◦ Common causes: genetic disorders, Rh incompatibility,
infection or disease, trauma, anoxia, ototoxic drugs,
prematurity
 Acquired: occurs sometime after birth
◦ Common causes: trauma, ototoxic drugs, middle ear
infections, infection, noise, systemic illness, barotrauma
 Prelingual vs. postlingual

35.  Identifies the auditory structures that are affected
 Conductive loss: damage to the outer or middle
ear
 Sensorineural loss: damage to the cochlea or
auditory nerve
 Mixed loss: simultaneous damage to the
conductive and sensorineural mechanisms

36.  Classification based on the aspects of audition
that are impacted
 Loss of hearing acuity: loss of precision of hearing
at different levels of loudness
 Decrease in language comprehension (occurs
with sensorineural loss)
◦ more difficult to manage

37.  Classification based on severity using decibel
system (dB)
 Hearing loss is represented by identifying the
threshold of hearing: where a person just begins to
hear
◦ Normal hearing: -10 to 15 dB
◦ Mild hearing loss: 26 to 40 dB
◦ Moderate hearing loss: 41 to 55 dB
◦ Severe hearing loss: 71 to 90 dB
◦ Profound hearing loss: 91 dB or higher

38.  Attenuation or reduction of the sounds heard in
the environment
 However, exaggerates sound of one’s voice and
chewing, because of bone conduction
 Slight to moderate loss in one or both ears,
typically not severe
 Medical or surgical intervention is usually
successful, so loss is usually temporary

39.  Most CHL is acquired, with middle ear fluid the
most common cause. Congenital causes include
anomalies of the pinna, external ear canal, TM,
and ossicles. Rarely, congenital cholesteatoma or
other masses in the middle ear may present as
CHL. TM perforation (trauma, OM), ossicular
discontinuity (infection, cholesteatoma, trauma),
tympanosclerosis, acquired cholesteatoma

40.  masses in the ear canal or middle ear
(Langerhans' cell histiocytosis, salivary gland
tumors, glomus tumors, rhabdomyosarcoma) may
also present as CHL. Uncommon diseases
affecting the middle ear and temporal bone that
may present with CHL include otosclerosis,
osteopetrosis, fibrous dysplasia, and osteogenesis
imperfecta.

41.  CHL can also be genetic. Conditions, diseases, or
syndromes that include craniofacial abnormalities
are often associated with conductive hearing loss
and possibly with SNHL. Pierre Robin, Treacher
Collins, Klippel-Feil, Crouzon, and branchio-
otorenal syndromes and osteogenesis
imperfecta . malformations of the ossicles and
middle-ear structures and atresia of the external
auditory canal.

42.  Most common cause: middle ear infections (otitis
media)
◦ Angle and shortness of Eustachian tube in children
allows organisms to enter easily
◦ Allergens (e.g., cigarette smoke) make more susceptible
◦ Interactions with other children spread infections (e.g.,
child-care centers)
 Other causes: ear wax (cerumen) blockage,
foreign objects, congenital malformations

43.  Most common type of hearing loss – slight to
profound loss of hearing in one or both ears
 Decrease in loudness, also decrease in speech
perception and ability to distinguish speech from
background noise
 Some also experience reduced tolerance for loud
noises or ringing in the ears (tinnitus)

44.  SNHL may be congenital or acquired. Causes of
SNHL include genetic, infectious, autoimmune,
anatomic, traumatic, ototoxic, and idiopathic
factors. The most common infectious cause of
congenital SNHL is cytomegalovirus (CMV), which
infects 1/100 newborns in the United States. Of
these, 6,000-8,000 infants per year will have
clinical manifestations, including approximately
75% with SNHL.

45.  Congenital CMV warrants special attention
because it is associated with hearing loss in its
symptomatic and asymptomatic forms; the hearing
loss may be progressive. Some children with
congenital CMV have suddenly lost residual
hearing at age 4-5 yr. Other less common
congenital infectious causes of SNHL include
toxoplasmosis and syphilis.

46.  Congenital CMV, toxoplasmosis, and syphilis may
also present with delayed onset of SNHL, months
to years after birth. Rubella, once the most
common viral cause of congenital SNHL, is now
very uncommon because of effective vaccination
programs. Prenatal infection with herpes is rare,
and hearing loss as the only manifestation is very
unusual

47.  Other postnatal infectious causes of SNHL include
Group B streptococcal sepsis in newborns and
bacterial meningitis. Streptococcus pneumoniae is
the most common cause of bacterial meningitis
that results in SNHL after the neonatal period; this
cause may become less frequent with the routine
administration of pneumococcal conjugate
vaccine.

48.  Haemophilus influenzae, once the most common
cause of meningitis resulting in SNHL, is now rare
owing to the Hib vaccine. Uncommon infectious
causes of SNHL include Lyme disease, parvovirus
B19, and varicella. Mumps, rubella, and rubeola,
all once common causes of SNHL in children, are
rare owing to vaccination programs

49.  Genetic causes of SNHL are probably responsible
for as many as 50% of SNHL cases. These
disorders may be associated with other
abnormalities, may be part of a named syndrome,
or may exist in isolation. SNHL often occurs with
abnormalities of the ear and eye and with
disorders of the metabolic, musculoskeletal,
integumentary, renal, and nervous systems.
Autosomal dominant hearing losses account for
about 10% of all cases of childhood SNHL.

50.  Waardenburg (types I and II) and branchio-
otorenal syndromes represent two of the most
common autosomal dominant syndromic types of
SNHL. Autosomal recessive genetic SNHL, both
syndromic and nonsyndromic, accounts for about
80% of all childhood cases of SNHL.

51.  Usher syndrome (types I, II, and III), Pendred
syndrome, and the Jervell and Lange-Nielsen
syndromes (a form of the long Q-T syndrome) are
three of the most common syndromic recessive
types of SNHL. Whereas children with an easily
identified syndrome or with anomalies of the outer
ear may be identified as being at risk for hearing
loss and monitored adequately,

52.  nonsyndromic children present greater difficulty.
Mutations of the connexin-26 and -30 genes have
been identified in autosomal recessive and
autosomal dominant and in sporadic
nonsyndromic patients with SNHL. Sex-linked
disorders associated with SNHL, thought to
account for 1-2% of SNHL, include Norrie disease,
the otopalatal digital syndrome, and Alport
syndrome.

53.  Chromosomal abnormalities such as 13-15-
trisomy, 18-trisomy, and 21-trisomy can also be
accompanied by hearing impairment. Patients with
Turner syndrome have monosomy for all or part of
one X chromosome and may have CHL, SNHL, or
mixed hearing loss. The hearing loss may be
progressive. Mitochondrial genetic abnormalities
may also result in SNHL.

54.  Agenesis or malformation of cochlear structures,
including the Scheibe, Mondini, Alexander, and Michel
anomalies, and enlarged vestibular aqueducts and
semicircular canal anomalies may be genetic. These
anomalies probably occur before the 8th wk of
gestation and result from arrest in normal
development, aberrant development, or both. Many of
these anomalies have also been described in
association with other congenital conditions such as
intrauterine infections (CMV, rubella).

55.  Many genetically determined causes of hearing
impairment, including both syndromic and
nonsyndromic, do not express themselves until
some time after birth. Alport, Alström, and Down
syndromes, von Recklinghausen disease, and
Hunter-Hurler syndrome are genetic diseases that
may have SNHL as a late manifestation

56.  SNHL may also occur secondary to exposure to toxins,
chemicals, and antimicrobials . Early in pregnancy, the
embryo is particularly vulnerable to the effects of toxic
substances. Ototoxic drugs, including aminoglycosides,
loop diuretics, and chemotherapeutic agents (cisplatin)
may also cause SNHL. Congenital SNHL may occur
secondary to exposure to these drugs as well as to
thalidomide and retinoids. Certain chemicals, such as
quinine, lead, and arsenic, may cause hearing loss both
prenatally and postnatally

57.  Trauma, including temporal bone fractures, inner
ear concussion, head trauma, iatrogenic trauma
(surgery, extracorporeal membrane oxygenation
[ECMO]), radiation, and noise may also cause
SNHL. Other uncommon causes of SNHL in
children include immune disease (systemic or
limited to the inner ear), metabolic abnormalities,
and neoplasms of the temporal bone

58.  Usually is present at birth as a congenital hearing
loss
 Half of the causes are unknown, the other half are
caused by genetics and heredity, infection, otitis
media, prematurity, pregnancy complications,
trauma
 Risk factors: influenced by maternal health, birth
process, hereditary factors, exposure to
medications, and disease

59.  Both permanent reduction of sound
(sensorineural) and additional temporary loss of
hearing (conductive)

60.  Identification: often begins with routine screening,
(e.g., newborn screening)
 Ongoing monitoring: understanding hearing loss
changes over time and to measure effects of
intervention

61.  Referral
 Screening
 Comprehensive Audiological Evaluation
 Hearing Aid Evaluation

62.  EDHI programs are present in most states, with the
goal to detect hearing loss while the infant is still in
hospital after birth
 Toddlers and preschoolers are referred if:
◦ show developmental delay
◦ have hereditary disposition for hearing loss
◦ develop disease or disorder that affects the auditory
mechanism
 All children are evaluated routinely in kindergarten,
and 1st-3rd grades, and 7th and 11th grades

63.  Infant Screening:
◦ Completed at birth in the hospital
◦ Typically uses otoacoustic emissions or evoked auditory
potentials as test measures
 Conventional Hearing Screening:
◦ Require the child to respond when a soft tone is
presented and heard (behavioral testing)
◦ Children who fail are either re-screened in two weeks or
referred for a comprehensive examination

64.  Assesses the type and degree of hearing loss,
speech discrimination, and auditory perception
 Case history
 Interview and observation
 Otoscopic examination
 Audiometry
 Objective measures
◦ Immitance, otoacoustic emissions (OAEs), evoked
auditory potentials (EAPs)

65.  12No differentiated babbling or vocal imitation
 18No use of single words
 24Single-word vocabulary of ≤ 10 words 30Fewer
than 100 words; no evidence of two-word
combinations; unintelligible 36Fewer than 200
words; no use of telegraphic sentences, clarity <
50%
 48Fewer than 600 words; no use of simple
sentences; clarity ≤ 80%

67. An audiogram provides the fundamental
description of hearing sensitivity. Hearing
thresholds are assessed as a function of
frequency using pure tones (sine waves) at octave
intervals from 250-8,000 Hz.
Earphones are typically used, and hearing is
assessed independently for each ear.
Air-conducted signals and bone-conducted signals
are elicited.

68.  In a normal ear, the air and bone conduction
thresholds are the same; they are also the same
in those with SNHL. In those with CHL, the air and
bone conduction thresholds differ. This is called
the air-bone gap; it indicates the amount of
hearing loss attributable to dysfunction in the outer
and/or middle ear.
 With mixed hearing loss, both the bone and air
conduction thresholds are abnormal, and there is
an air-bone gap.

69.  Another measure useful in describing auditory
function is the speech recognition threshold
(SRT), which is the lowest intensity level at which
a score of approximately 50% correct is obtained
on a task of recognizing spondee words. Spondee
words are two-syllable words or phrases that have
equal stress on each syllable (baseball, hotdog,
pancake). Listeners must be familiar with all the
words for a valid test result to be obtained.

70.  The SRT should correspond to the average of
pure-tone thresholds at 500, 1,000, and 2,000 Hz,
the pure-tone average (PTA). The SRT is relevant
as an indicator of a child's potential for
development and use of speech and language; it
also serves as a check of the validity of a test
because children with nonorganic hearing loss
(malingerers) may show a discrepancy between
the PTA and SRT

71.  Hearing testing is age-dependent. For children at
or above the developmental level of a 5 or 6 yr
old, conventional test methods can be used. For
children 2½-5 yr old, play audiometry can be
used. Responses in play audiometry are usually
conditioned motor activities associated with a
game, such as dropping blocks in a bucket,
placing rings on a peg, or completing a puzzle.

72.  The technique can be used to obtain a reliable
audiogram for a preschool child. For those who
will not or cannot repeat words clearly for the SRT
and word intelligibility tasks, pictures can be used
with a pointing response.

73.  For those between the ages of about 6 mo and
2½ yr, visual reinforcement audiometry (VRA) is
commonly used. In this technique, the child is
observed for a head-turning response upon
activation of an animated (mechanical) toy
reinforcer. If infants are properly conditioned, by
giving sounds associated with the visual toy cue,
VRA can provide reliable estimates of hearing
sensitivity for tones and speech sounds.

74.  In most applications of VRA, sounds are
presented by loudspeakers in a sound field, so no
ear-specific information is obtained. Assessment
of an infant is often designed to rule out hearing
loss that would affect the development of speech
and language. Normal sound field response levels
of infants indicate sufficient hearing for this
purpose despite the possibility of different hearing
levels in the two ears.

75.  Used as a screening device for infants younger
than 5 mo, behavioral observation audiometry
(BOA) is limited to unconditioned, reflexive
responses to complex (not frequency-specific) test
sounds, such as noise, speech, or music
presented using calibrated signals from a
loudspeaker or uncalibrated noisemakers.
Response levels can vary widely within and
among infants and usually do not represent a
reliable estimate of sensitivity

76.  This is a standard part of the clinical audiologic
test battery and includes tympanometry. Acoustic
immittance testing is a useful objective
assessment technique that provides information
about the status of the middle ear. Tympanometry
can be performed in a physician's office and is
helpful in the diagnosis and management of OM
with effusion, a common cause of mild to
moderate hearing loss in young children

77.  This technique provides a graph of the ability of
the middle ear to transmit sound energy
(admittance, or compliance) or impede sound
energy (impedance) as a function of air pressure
in the external ear canal.
 Abnormalities of the TM can dictate the shape of
tympanograms and thus obscure abnormalities
medial to the TM.

78.  Children with OME often have reduced peak
admittance or high negative tympanometric peak
pressures .
 The more rounded the peak (or "flat" in an absent
peak), the higher is the probability that an effusion
is present .

79. FIGURE 2 Typical tympanograms showing, for each, the estimated probability of
MEE
Smith, C. G. et al. Pediatrics 2006;118:1-13
Copyright ©2006 American Academy of Pediatrics

80.  Reflexes are usually absent in those with CHL due
to the presence of an abnormal transfer system;
thus, the ART is useful in the differential diagnosis
of hearing impairment. ART also is used in the
assessment of SNHL and the integrity of the
neurologic components of the reflex arc, including
cranial nerves VII and VIII.

81.  The ABR test is used for newborn hearing
screening, to confirm hearing loss in young
children, to obtain ear-specific information in
young children, and to test children who cannot,
for whatever reason, cooperate with behavioral
test methods. It is also important in the diagnosis
of auditory dysfunction and of disorders of the
auditory nervous system. The ABR test is a far-
field recording of minute electrical discharges from
numerous neurons

82.  As an audiometric test, it provides information on
the ability of the peripheral auditory system to
transmit information to the auditory nerve and
beyond. It is used also in the differential diagnosis
or monitoring of central nervous system
pathology. For audiometry, the goal is to find the
minimum stimulus intensity that yields an
observable ABR

83.  Plotting latency versus intensity for various waves
also aids in the differential diagnosis of hearing
impairment
 The ABR is recorded as 5-7 waves. Waves I, III,
and V can be obtained consistently in all age
groups; Waves II and IV appear less consistently

84.  The ABR test has two major uses in a pediatric
setting. As an audiometric test, it provides
information on the ability of the peripheral auditory
system to transmit information to the auditory
nerve and beyond. It is used also in the differential
diagnosis or monitoring of central nervous system
pathology.

85.  During normal hearing, OAEs originate from the
hair cells in the cochlea and are detected by
sensitive amplifying processes. They travel from
the cochlea through the middle ear to the external
auditory canal, where they can be detected using
miniature microphones. Transient evoked OAEs
(TEOAEs) may be used to check the integrity of
the cochlea.

86.  In this test, a hand-held instrument is placed next
to the opening of a child's ear canal and 80-dB
sound is delivered that varies in frequency from
2,000-4,500 Hz in a 100-msec period. The
instrument measures the total level of reflected
and transmitted sound. Some physicians have
found this device useful to help gauge the
presence or absence of middle-ear fluid