– Responsible for our ability to hear very

 soft and very loud sounds

– OAEs are a by-product of OHC motility

SOAEs are continuous tonal signals that occur without any stimulation

• Present in about 50% of normal ears

– i.e., normal inner ear and middle ear

– A person may have multiple SOAEs at several different frequencies

not used clinically

• Otoacoustic emissions that are produced in response to an acoustic stimulus

• Two kinds of evoked OAEs are commonly used by clinical audiologists

1. Transient evoked OAEs (TEOAEs)

2. Distortion product OAEs (DPOAEs)

used clinically

stimulus is in the ME

• Evoking stimuli

– two choices:

– Clicks

– Tone pips (very brief pure tones)

• What the ear produces in response

– A broadband sound

• Evoking stimuli:

– Two steady pure tones

• Presented simultaneously

• Referred to as “primaries”

– Primary frequencies: f1 and f2

• f2 > f1

• Typically f2/f1 = 1.22 (f1 = f2/1.22)

• In clinic, test f2’s with frequencies similar to audiometric frequencies

– Primary levels: L1 and L2

• L2 < L1

• In clinic, usually L1 = 65 dB SPL, L2 = 55 dB SPL

• Response: – Several pure tones, all mathematically related to the primaries (f1 and f2)

• e.g., 2f1-f2; 2f2-f1; 3f2-2f1

– Primary levels & frequencies are chosen to maximize the emission at 2f1– f2

• Ex: f2 = 2000 Hz, f1 = 1640 Hz – fDP = 1280 Hz

• A probe is placed in the ear canal

– Has 1 or 2 loudspeakers and a microphone

2 speakers: distortion

1 speaker: transient

– Usually covered with a foam plug like those used for insert phones

– Patient must be quiet and still

– Takes 1-5 minutes per ear, depending on the specific test

• To get a normal EOAE

– Cochlea has to generate the emission

• Requires no more than a mild SNHL (i.e., loss

< 40 dB HL) for stimuli used in the clinic

– Ear has to transmit sound two ways:

• Stimulus has to get to the cochlea,

• Emission has to get to the ear canal

• Requires normal conductive mechanism

Auditory evoked potentials: EEG

• Measuring electrical activity from the brain is called electroencephalography (EEG)

• When we observe changes in brain activity in response to specific stimuli, we call these changes evoked potentials (EPs)

– That is, electrical potentials that are evoked by a stimulus or event

– Can measure EPs for all sorts of stimuli

• Compared to ongoing neural activity, responses to stimuli are very small

• How do we measure a response then? – By averaging: • Ongoing EEG activity is random, with both positive (+) and negative (―) values

• A response is always + or always ―

• If we sum the EEG activity over time, the response will emerge from the noise

• Lots of different responses can be recorded, at various latencies

– Latency = the timing of a response relative to the stimulus

• Example: – Stimulus is presented at 0 ms – Response occurs at 150 ms – Response latency = 150 ms

the timing of a response relative to the stimulus

Auditory evoked potentials: ECoG

• The earliest responses that are recorded come from the cochlea

– Measurements of these responses are referred to as electrocochleography (ECoG)

• The latest responses that are recorded come from the auditory cortex

– These responses are called auditory eventrelated potentials (ERPs)

Auditory evoked potentials: ECoG

• The earliest responses that are recorded come from the cochlea

– Measurements of these responses are referred to as electrocochleography (ECoG)

• The latest responses that are recorded come from the auditory cortex

– These responses are called auditory eventrelated potentials (ERPs)

Auditory evoked potentials: ABR

• The response that has the widest clinical application is the auditory brainstem response (ABR)

– Occurs in the first 10-15 ms after the stimulus

– Generated by the auditory nerve and auditory brainstem – Thus, normal ABR implies normal cochlea, auditory nerve and brainstem

• Three or four electrodes

– 1 on each ear (mastoid or ear lobe)

– 1 on vertex, and/or 1 on forehead

• Have to avoid electrical noise

– Test room must be electrically shielded

– Should use insert earphones

• Have to avoid muscle artifact

– Patient has to be very relaxed

• Evoking stimuli: Clicks or tone pips

– Presentation rate • Usually 33.1 clicks per second

– Presentation level • Depends on purpose of test

• Response: A set of 5 to 7 small waves – Named using Roman numerals I - VII

• Latencies

– Individual Waves

• Typically look at waves I and V

– Interpeak latency

• Difference between waves in one ear

• Typically I to V

– Interaural latency

• Difference between ears for a given wave

• Typically wave V

• Amplitudes

– Individual wave amplitudes

– Amplitude ratio between Wave V and Wave I

• “V/I ratio”

– Amplitude is highly variable and not typically used diagnostically

• Plot of wave V latency as a function of stimulus level

• ABR threshold = Lowest level at which a reliable wave V can be measured

• Audiological purposes

– To assess hearing sensitivity in difficult-totest patients

• Sometimes done under sedation and/or in the operating room

• Intraoperative monitoring

– During surgeries where the cochlea or auditory nerve is at risk of being damaged

• Neurological purposes

– Assess health of auditory brainstem

– Done when audiological evaluation or other symptoms suggest a retrocochlear problem

• i.e., a problem at a point in the auditory system higher than the cochlea

– Much less expensive than an MRI and can rule out the need for one

ABR is not as accurate as an MRI, however

– Taken at 1, 5 and 10 minutes after birth

– Assess respiratory effect, muscle tone, heart

rate, color, reflex, irritability

– A score of 1-10 is given

– Contraction of muscles around eyes in

response to loud sound

– Problems: agreement among technicians, can miss mild to moderate losses

– Approx. 12,000 children each year

– Up to 3 per 1000 births each year

• In 2007, approx. 91.5% of all newborns screened for hearing loss at birth

– In Alabama (2004); 96.32% of newborns screened

• Normal speech and language development requires extensive input during 1st year of life and up to the first 3 years

• Recent research suggests that early identification and intervention promotes excellent speech and language outcomes for children with hearing loss

Screen using OAEs, then do ABR if baby fails

• Otoacoustic emissions (OAEs)

– Either TEOAEs or DPOAEs

– Numerous portable devices available that have automated protocols

• Nurses, volunteers, technicians may complete screening

• Audiologist supervises

– Issues to consider

• Supplies relatively inexpensive (eartips)

• Very good ability to detect conductive and cochlear hearing loss (moderate through profound, still miss some mild losses)

• May miss neural hearing losses. Why?

• Very susceptible to false positive from vernix, transient middle-ear fluid

• Auditory brainstem response (ABR)

– Portable units can be taken to baby’s bedside (nursery or mom’s room)

– Automated units exist

• Nurses, volunteers, technicians may do the screening with these

• Audiologist supervises

– Issues to consider

• More expensive (supplies = electrodes and eartips vs. just eartips)

• Will catch conductive, cochlear, and some neural losses (may still miss some mild losses). Why?

• Much less susceptible to false positive from vernix, transient middle-ear fluid as compared to OAEs. Why?

1. Caregiver concern regarding hearing, speech, language, or developmental delay

2. Family history of permanent childhood hearing loss

3. NICU stay > 5 days or any length for certain conditions including: assisted ventilation, exposure to ototoxic meds, hyperbilirubinemia requiring exchange transfusion

4. In utero infections such as CMV, herpes, rubella, syphillis, and toxoplasmosis

5. Craniofacial anomalies, including those affecting pinna, ear canal, ear tags, ear pits, and temporal bone anomalies

6. Physical findings, such as a white forelock, associated with a syndrome that has SNHL or permanent CHL as a component

7. Presence of a syndrome associated with hearing loss or progressive/late-onset hearing loss (examples: neurofibromatosis, Usher, Waardenburg, Alport, etc.)

8. Neurodegenerative disorders.

9. Certain post-natal infections (example:meningitis)

10.Head trauma, especially those requiring hospitalization for basal skull/temporal bone fractures

11.Chemotherapy

– Short hospital stays

 – Follow-up

 – False positives

• Important to keep low

– Often screen second time before leave hospital

• Careful parent/caregiver counseling

Early Hearing Detection and Intervention (EHDI)

– 3 components:

1. Screening by 1 month (typically in hospital)

2. Identification by 3 months

 Diagnostic testing of infants failing screening to specify degree of

hearing loss or actual normal hearing

• Intervention by 6 months

Manage hearing loss, hearing aids, early intervention/therapy

programs

1. Identify hearing loss by 3 months 

Need diagnostic info regarding the hearing loss, not just screening info

2. Begin intervention by 6 months 

Need at least some threshold information

Behavioral Audiometry Techniques

– Behavioral Observation (Audiometry)

• < 6 mos.

– Visual Reinforcement Audiometry (and related

 techniques)

• 6 mos. – 2 yrs. (NICU graduates often not until 6 ½

to 8 mos. corrected age)

– Conditioned Play Audiometry

• 2 yrs. to 5 yrs.

– Adult techniques

• 4/5 yrs. +

Behavioral Observation (Audiometry): BO(A)

Technique

– Play sound and look for response

– Response is not “conditioned”, looking for any response to sound

• Startle

• Cessation of sucking

• Eyes widening

Behavioral Observation (Audiometry): BO(A)

 Issues

– May only see response to high sound levels, even if baby

 has normal hearing

– Highly subjective!

– This is NOT audiometry, use as a last resort only!

Visual Reinforcement Audiometry (VRA)

• Technique

– Conditioned Response

• Child turns head in response to sound

• “Conditioned” because have paired stimulus, response, and

reinforcement during training/conditioning phase

– Training stimulus must be perceptible

» Audible

» Vibrotactile for severe to profound losses

– Two testers

• One in booth with child

• One at audiometer

• Both testers vitally important to success

Visual Reinforcement Audiometry (VRA)

Role of person in booth

– Keep child attentive at midline

– Social reinforcement for child

– Don’t compete with stimulus, reinforcer

• “Don’t be too interesting”

– Maintain quiet environment

– Maintain rapport with and cooperation of the

parent

– Quick assistance with earphones

Visual Reinforcement Audiometry (VRA): Stimuli

– Speech

– Tones (warbled or pulsed), sometimes narrow bands of

noise

– Order of testing

• Depends on reason for eval

• Speech, first or last?

– Getting SDT

– Normal response to speech doesn’t rule out hearing loss

• Order of tones:

– One possibility: 2000, 500, 4000, 250, 1000, 8000 Hz

• Be prepared for session to end at any time

Visual Reinforcement Audiometry (VRA): Transducers

– Speakers in booth

• Which ear testing?

– Headphones

• Inserts (typically more acceptable to babies)

• Supra-aural

– Bone Vibrator

– Always try headphones!

Conditioned Play Audiometry (CPA)

• Technique

– Conditioned response to sound

• Do play activity when hear sound

– Drop block

– Push a button to “make” a toy light up

– Place peg in peg-board

• Conditioned because pairing the behavior with the stimulus during training phase

– One or two testers

• Two testers is ideal and more necessary for younger children

• Make response fun for child

– Important to have a variety of activities

– May use lighted toys as reinforcers

– Tester in booth important role here too

• Transducers

– Usually headphones, use speakers (sound field) as last resort

– Bone Vibrators

• Test Stimuli

– Speech Stimuli

• Must be appropriate for language level

• Choose response understandable to tester

• Often picture pointing

– SRT

– Speech-recognition

» NU-CHIPS (4 alternative)

» WIPI (6 alternative)

» LNT (Open set)

1. Microtia

2. Anotia

Very small size pinna

Anotia

Absent pinna

1. Stenosis

2. Atresia

3. CHARGE syndrome

4. External Otitis

5. Growths in the canal: Osteomas & Exostoses

Stenosis

Narrowing of the ear canal

Atresia

Cartilaginous or bony portion or the entire ear

 canal has not formed at all

– Treacher Collins syndrome

CHARGE syndrome

Associated with anomalies of the pinna and

 external auditory canal

External Otitis

– Infection that occurs in the skin of the external auditory canal (swimmer’s ear – often occurs with people who have water trapped in their ears)

– Can occur from allergic reactions to earplugs, hearing-aid earmolds, soaps, etc…

Osteomas

• Bony tumors in the EAC

• Not a problem unless they cause a hearing loss/lead to external otitis – what type of loss?

Exostoses

Bony protrusions in the bony wall of the EAC

1. Otitis Media (OM)

2. Acute Otitis Media (AOM)

3. Otitis Media with Effusion (OME)

4. Cholesteatoma

5. Otosclerosis

• Inflammation of the middle ear

• Types:

– Acute Otitis Media

– Otitis Media with

Effusion

• Effusion – fluid that accumulates in the middle ear space

– Produced by cells lining the ME

– Ranges from thin (serous) to glue-like

Impact of Otitis Media

• Approx. 90% of children have otitis media before school age (most frequent between 4 mos. and 4 yrs)

• During Year 2000

– 16 million doctor’s visits for OM

– 13 million prescriptions for antibiotics

• Estimated annual costs (direct and indirect) $3 to $5 billion

Acute Otitis Media (AOM)

• An infection in middle ear

• Usually secondary to upper respiratory infection (URI)

• Symptoms include

– Infected fluid in middle ear

– Bulging TM

– Red TM

– Otalgia (ear pain)

– Fever

– Otorrhea (drainage - if TM perforated/tube in place)

– Rapid onset of symptoms

AOM Stages

• Patient has a URI

• Bacteria (or virus) associated with URI migrate from back of throat to ME

– How?

• Bacteria multiply in ME, use oxygen, create negative

pressure in ME

– Eustachian-tube dysfunction (ETD) due to swelling of

mucosa contributes to problem

• Cells lining ME secrete fluid that becomes infected

– ETD aggravates – fluid doesn’t drain

• They get more URIs

• Eustachian tube characteristics

– Open more frequently (feeding, crying)

– Angle from pharynx to middle ear is not as steep

• Watch and wait

– May resolve on own

• Treat with antibiotics

• Very young children (<6 mos) always go straight to antibiotics

• Older children and adults, approach depends on severity of symptoms and/or certainty of diagnosis

Otitis Media with Effusion (OME)

• Otitis Media with effusion that persists beyond 8 weeks

• Chronic effusion, but no active infection

– Unheard of before antibiotics

• Since fluid not infected, child not sick.

• Fluid may cause hearing loss!

• Chronic negative middle ear pressure creates a vacuum

– Fluid drawn out of cells lining middle ear

• Fluid present during AOM never clears due to ETD

• If causes hearing loss

– What type of hearing loss?

– What is maximum amount of hearing loss?

– What will speech-recognition results be?

• What type of tympanogram?

– Watch and wait, why this?

– No antibiotics, no infection

– Pressure-equalizing (PE) tubes

Cholesteatoma

• A pseudotumor in the middle ear

– Composed of accumulation of skin, keratin, fats

– Starts when skin cells enter middle ear through perforation

• Very destructive

– May erode ossicles

– Can erode bone and spread into pharynx or brain

• Can cause conductive hearing loss

• Can cause pain, facial nerve symptoms

– Surgery

• Serious medical problem, hearing issues secondary until treated

– Must be careful to remove entire cholesteatoma or will regrow

– May have permanent conductive hearing loss post surgery

• Depends on what structures were affected

Otosclerosis

• Abnormal growth of spongy bone tissue over the stapes footplate

– Interferes with movement of stapes

• Hereditary in many cases (50-70%)

• More frequent in women than men

• Usually first noticed in 20s

– Will worsen during pregnancy

• Symptoms

– Progressive conductive hearing loss

• Starts in low frequencies

• Eventually, see flat moderate CHL

– Unique feature: Carhart’s notch

• Depressed bone conduction threshold at 2000 Hz

• Results from disruption of inertial bone conduction

– Stapedectomy Surgery

• Stapes is removed

• Graft is used to seal the oval window

• Stapedial prosthesis is placed

– 95-99% of patients have smaller air-bone gaps post

surgery

– Hearing aids

• People with conductive hearing loss tend to be extremely successful with hearing aids

UNHS is accomplished using pure tone behavioral testing.

T or F

False

OAEs and ABRs (Objective)

The Tympanic membrane produces OAEs.

T or F

False

OHC produce OAEs

Puretone signals are used to generate TEOAE responses.

T or F

False

DPOAEs are

Pure tone signals are used to generate DPOAEs

T or F

True

The ongoing EEG activity is random.

T or F

The electrical response from the brainstem is random.

T or F

False

Its either all + or all -

is the most robust

the one we are most intereste in

URI

ETD

Multiplying bacteria in the ME

Otitis Media results in a conductive hearing loss.

T or F

The most notable audiological feature of otosclerosis is?

For a mild high frequency NIHL reflexes will be absent at 4000 Hz.

T or F

False

present at reduced SL b/c its sensorineural

Rubella

Cytomegalovirus (CMV)

Meniere's Disease

Noise-Induced HL (NIHL)

Ototoxicity

Presbycusis

Acoustic Neuroma

– A concern if caught during 1st trimester

– Epidemic during 1964 and 1965

– Babies tend to be born smaller and develop more slowly – Brain damage, blindness, heart defects, SNHL

– Vaccine in 1969 reduced number of cases but still a concern among poor and groups who refuse vaccinations

– Typically a harmless illness if not associated with pregnant mother

 – When fetus is affected a number of devastating symptoms can be present, in addition to hearing loss

 – Can be contracted before birth through placenta, during birth via cervix, and after birth via mother’s milk

 – Perhaps screening after birth might help with prevention/intervention program

• can be any cold/flu sympoms
• permanent
• symptoms can progress as you get older

• Classic symptoms:

– Sudden attacks of vertigo

• Very debilitating

• Can last 2-4 hours or more

• May be accompanied by nausea and vomiting

– Roaring tinnitus

– Unilateral hearing loss

• Later stages: may be bilateral

– Aural fullness

• Hearing loss characteristics

– Fluctuating and progressive, SNHL

– Very poor speech recognition

• Cause:

– Root cause believed to be endolymphatic hydrops

• Over production or under absorption of endolymph

– Low salt diet and diuretics

• Reduce fluid retention

– Vestibular suppressant drugs

– Surgery

• Endolymphatic sac decompression

• Shunt

• Cut vestibular nerve

• Labyrinthectomy

• Noise = an acoustic signal which can negatively affect the physiological or psychological well being of an individual

– Can be any sound!

• Excessive noise exposure is one of the most common causes of SNHL

– TTS: temporary threshold shift

– PTS: permanent threshold shift

• It’s preventable!

– Education

– Noise reduction or avoidance

– Hearing protection

– Stereocillia become floppy and loose contact with

tectorial membrane

– Loss of stereocillia and disarray

– Loss of OHCs

– Loss of IHCs

• Which occurs depends on level of “noise” and length of duration.

OHC are damaged first, then IHC

Pathophysiology of NIHL

• When sufficient numbers of hair cells are lost:

– cochlear nerve fibers degenerate

– may then see structural and functional changes in central system

– Sensorineural loss with poorest thresholds at 3000 – 6000 Hz, recovery at 8000 Hz

– “Noise Notch” or “4k Notch”

• Certain medications can damage the cochlea and/or the vestibular system

• Aminoglycoside antibiotics

– The “mycins,” e.g., neomycin, kanamycin, streptomycin, gentamycin

– Used for drug-resistant bacteria or very severe infections

• Chemotherapy drugs

– Cisplatin

• Widely used chemotherapy drug

• Loop diuretics – widely used medications for patients with heart failure, fluid retention problems, pneumonia, kidney problems.

– Two most common:

• Furosemide (Lasix)

• Ethacrynic acid

• Salicylates

– Treatment of arthritis, rheumatic fever, and connective

tissue disorders

– Aspirin

– Ototoxic in large doses, may be reversible

• Quinine

– Treatment of malaria, nocturnal leg cramps

– Tinnitus, hearing loss, vertigo

– Symptoms generally temporary

– With high doses, hearing loss and tinnitus may be permanent

• Monitoring for ototoxic effects

– High frequencies usually affected first

– DPOAEs used in some monitoring programs

• Hearing loss and aging

– 30% of adults > 65 have significant hearing loss

• Prevalence increases to 75% in 85+ age group, which is the fastest-growing demographic

– Primary causes of hearing loss in the elderly

• Noise exposure

• Ototoxicity

• Hearing loss due to aging

– Affects ≈37% of population over 75 years

– More prevalent in men than in women

• Differences in noise exposure? Diet?

– Audiogram

• Sloping high-frequency hearing loss

– Women tend to show less slope than men

• Gradual onset and progression

– Progresses more rapidly in men

• Chief difficulty: Understanding speech in noise

– May have poorer than expected word recognition

» Degeneration in central auditory system?

• A retrocochlear tumor

• A tumor on the VIIIth cranial nerve

– Typically arises from the Schwan’s cells on the vestibular branch

• More appropriate term: Vestibular Schwanomma

– These tumors are usually benign and slow growing

– Very treatable if caught early enough

• Audiologists are often the first to raise suspicion can be removed surgically from the auditory nerve after surgery, it will lead to severe to possible profound HL

• Signs that may appear during a standard audiological evaluation:

1. Unilateral (or asymmetrical) high-frequency hearing sensorineural hearing loss

• Most acoustic neuromas are unilateral

• High-frequency loss is because of the tonotopic arrangement of nerve fibers

2. Poorer-than-expected word recognition

Especially at high presentation levels

This is called rollover

3. Absent acoustic reflexes, despite having a

normal tympanogram

4. Acoustic reflex decay

 Have reflex but it fails to persist (“hold”) for 10 seconds

Other signs that may from case history:

– Unilateral tinnitus

– Dizziness/dysequilibrium/vertigo

• When any of these audiometric signs occure, need to perform special audiometric tests

– Otoacoustic emissions (OAEs)

• Normal OAEs indicate normal OHCs

• Suggest hearing loss due to a retrocochlear problem

– Auditory brainstem response (ABR)

• Abnormal interpeak latencies and interaural latencies can indicate an acoustic neuroma

• If suspect acoustic neuroma/can’t rule it out

– Refer patient to ENT

• Counsel very carefully!

• ENT will usually order imaging (MRI)

• Treatment: almost always surgery

– Can hearing be preserved? Depends on

• Size and location of tumor

• Surgical approach used

– If hearing preservation attempted, audiologist may monitor hearing during surgery using ABR

• Other conditions that cause similar audiometric and ABR results

– Acoustic neuritis

• Inflammation of auditory nerve

– Multiple sclerosis

• Breakdown of myelin, the insulating layer around many neurons

• Can affect speech in noise especially

Chromosomal disorder (chromosome 21)

– An extra copy

Characteristics of Down Syndrome

– Upslanting palebral fissures (eye slits)

– Relatively large tongue with tendency to protrude

– Small chin

– Small fingers

– Developmental delay

– Small ears

Health problems with Down Syndrome

– heart disease

– Dementia

– Hearing problems

– Problems with the intestines, eyes, thyroid

and skeleton

Hearing Issues of Down Syndrome

– Hearing loss is very common

– Approximately 75% of children have unilateral or bilateral hearing loss

– Conductive disorders are most prevalent.

– Degree varies from mild to moderate

– Impacted cerumen

– Retracted tympanic membrane and ME effusion

Causes of Hearing Loss in Down Syndrome

– Susceptibility to URI

– Congenital malformations of the nasopharynx and Eustachian tube

– Congenital ossicular chain malformations or destruction of ossicles caused by infection

A genetic disorder – either inherited or the result of spontaneous genetic mutation

• Mutations in the TCOF1 gene .

• The TCOF1 gene provides instructions for making a protein called treacle, which production is reduced by the mutation.

• Precise function of this protein is unknown, thought to play a critical role before birth in the development of bones and other tissues in the face.

– Autosomal dominant pattern of inheritance

• one copy of the altered gene is sufficient to cause the disorder

60% mutations in the gene.

40% inherited

50/50 chance

– Downward slanting eyes

– Cleft of lower eyelid

– Small cheekbones

– Small jaw

– Malformations of external ear

– associated with stenosis or atresia of ear canal

– Cleft or incomplete soft palate

– Dental problems

– Pinna malformations – of varying degrees

– Stenosis – of varying degrees

– Atresia – of varying degrees

– ME malformations – poorly developed or absent

– Congenital bilateral CHL is most common

– Degree can range from mild to moderate

• Hereditary syndrome

• Characteristics

– Retinitis pigmentosa

• A degeneration of retina

• Progressive

– Congenital hearing loss

• Ranges from moderate to profound

• Typically not progressive

• Sensorineural HL

• Usher syndrome is a recessive disorder.

– a person must inherit an affected gene from each parent in order to have the disorder

– a person with one changed gene does not have the disorder, but can pass either the changed or the unchanged gene on to his or her child

• An individual who has one changed Usher Syndrome gene is a carrier.

1 in 4 chance, 25%

When two carriers of the same Usher syndrome gene have a child together, with each birth there is a:

1. 1-in-4 chance of having a child with Usher syndrome

2. 2-in-4 chance of having a child who is a carrier

3. 1-in-4 chance of having a child who neither has Usher syndrome nor is a carrier

– Incomplete development or atrophy of basal end of organ of corti in the cochlea

– Atrophy of stria vascularis and spiral ganglion cells

– Typically have greater hearing loss in the high frequencies compared to low frequencies

– Some researchers have reported 90% of cases have severe to profound hearing loss

With Down Syndrome, SNHL is the most common.

T or F

False

It's conductive

With Treacher Collins Syndrome, conductive losses are common.

T or F

With Usher Syndrome, conductive losses are common.

T or F

False

Sensorineural