The Audiology Clinic is a Section of the
Otolaryngology, Head and Neck Surgery Service, in the Department of
Audiologists are professionals trained in the assessment and treatment of hearing and balance disorders. The Audiology clinic provides a full range of audiologic services, including pediatric evaluations, hearing conservation, adult evaluations, auditory evoked responses, hearing aid evaluations and dispensing, and cochlear implants. Vestibular function testing is provided for patients with dizziness and balance disorders. Audiologists participate in Tripler AMC Craniofacial Team, the TAMC Cochlear Implant Team, and the Traumatic Brain Injury (TBI) Team.
Newborn hearing screening:
Audiology technicians make all efforts to complete hearing screening for all newborns, prior to discharge as part of the universal newborn hearing screening program. Newborn hearing screening is simple and painless and most times takes only a few minutes. Testing is completed by using Otoacoustic Emissions (OAEs) or screening Auditory Brainstem Response (ABR) testing. In some cases, both tests are used.
Otoacoustic Emissions (OAEs): are inaudible sounds measured from the outer hair cells in the cochlea in the inner ear, in response to specified tones or click stimuli. The emissions can be measured my inserting a small probe in the ear canal.
Auditory Brainstem Response (ABR) testing: is an auditory evoked response that originates from the auditory nerve. Electrodes are taped to the baby's head, and brain wave activity is recorded in response to click stimuli. ABR provides information as to the integrity of the hearing nerve and the pathway to the brainstem.
If an infant does not pass initial
hearing screening, re-screen will be completed prior to discharge, if
time permits. If patient is discharged prior to completing re-screen,
the Audiology clinic will contact patient's family to schedule
outpatient re-screen. If the infant does not pass the out-patient
re-screen, patient will be referred to an audiologist for diagnostic
ABR. Diagnostic ABR is completed to assess the integrity of the pathway
from the hearing nerve to the brainstem and to estimate patient's
hearing thresholds. Testing is completed while patient sleeps. Some
babies return for hearing monitoring even if newborn screening is
passed, due to having an indicator for possible late-onset hearing loss
(low birth weight, family history of permanent childhood hearing loss,
congenital infection, syndrome with associated hearing loss).
Type of hearing loss
Conductive Hearing Loss:
Conductive hearing loss occurs when sound is not conducted efficiently through the outer ear canal to the eardrum and the middle ear bones (ossicles) of the middle ear.
Examples of conditions that may cause conductive hearing loss include:
- Conditions associated with middle ear pathology such as fluid in the middle ear from colds, allergies , poor Eustachian tube function, ear infection (otitis media), perforated eardrum, or benign middle ear growth (cholesteatoma)
- Impacted earwax (cerumen)
- Infection in the ear canal (external otitis)
- Presence of a foreign body
- Absence or malformation of the outer ear, ear canal, or middle ear structures
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlear) or to the nerve pathways from the inner ear (retrocochlear) to the brain. Sensorineural hearing loss usually cannot be medically or surgically corrected. Most often, it is a permanent hearing loss.
Sensorineural hearing loss can be caused by diseases, birth injury, drugs that are toxic to the auditory system, and genetic syndromes. Sensorineural hearing loss may also occur as a result of noise exposure, viruses, head trauma, aging, and tumors.
Mixed Hearing Loss:
Sometimes a conductive hearing loss occurs in combination with a sensorineural hearing loss. There may be damage in the outer or middle ear and in the inner ear (cochlear) or auditory nerve. When this occurs, the hearing loss is referred to as a mixed hearing loss.
Hearing Evaluation: determines the patient's hearing acuity relative to adult hearing levels to determine if a hearing loss is present. When there is a hearing loss, the type and degree, or severity is also determined. The information is used to determine if medical or surgical intervention may be indicated. Patients may also be evaluated for hearing aid candidacy. Referrals are made to an ENT (Ear, Nose, and Throat physician) as needed.
Tympanometry: assesses the status of the middle ear, which consists of the tympanic membrane (eardrum) and three small bones (ossicles) that connect the eardrum to the inner ear. Middle ear problems can often be treated medically or surgically.
Acoustic reflexes (ARs): are measured from the middle ear. ARs evaluate acoustic reflex pathways, which include cranial nerves (CN) VII and VIII and the auditory brainstem.
Otoacoustic Emissions (OAEs): are
inaudible sounds measured from the outer hair cells in the cochlea in
the inner ear, in response to tones or click stimuli. The emissions can
be measured with a small probe placed in the ear canal.
Pediatric Hearing Evaluation
Behavioral hearing evaluations are used with children who are old enough to sit up unassisted and respond to sounds by turning their head (around 6 months of age), or by playing a listening game.
Visual Reinforcement Audiometry (VRA): is a method of testing children who are functioning at a developmental age between 6 months and 2 years old. The child is conditioned to turn to a sound source. When the child looks to the source when the sound is presented, a reinforcement toy is turned on to "reward" the child.
Conditioned Play Audiometry (CPA):
is a method used with children between 2 and 4 years of age. The child
is conditioned to perform an activity each time a sound is heard. The
activity may be dropping a toy in a bucket, or putting a peg in a hole.
The child is trained to wait, listen, and then respond.
Hearing Conservation Program
Hearing Conservation is a program for active duty and DoD employees who are exposed to occupational noise. Testing is typically completed annually. If a patient shows a significant shift in hearing threshold at an initial and follow-up test, the patient will be referred for a comprehensive hearing evaluation with an audiologist. A profile for permanent hearing loss will be provided when necessary. In addition to monitoring hearing, the hearing conservation program educates patients on use of hearing protection.
Treatment for Hearing Loss
- Hearing Aids
- Bone Anchored Hearing Aids (BAHA)
- Cochlear Implants
Patients with hearing loss are evaluated for hearing aid candidacy. If it is determined that the patient would benefit from hearing aids, a referral is made so that hearing aid medical clearance can be obtained from an ENT physician. Hearing aids are made in many different styles from completely-in-the-canal to behind-the-ear. Hearing aids are provided at no charge to active duty and family members of active duty. Retirees can purchase hearing aids through the Retiree at Cost Hearing Aid Program (RACHAP). Patients are seen in the RACHAP program on a space available basis.
Bone Anchored Hearing Aids (BAHA):
The BAHA utilizes direct bone conduction, allowing the bone to transfer sound to a functioning cochlea, by bypassing the middle ear. The sound processor couples to an abutment, connected to a small titanium implant. The BAHA is indicated for patients with conductive hearing loss who cannot successfully use conventional hearing aids (i.e., chronic middle ear disease, atresia). Patients with single-sided-deafness can also benefit from a BAHA.
A cochlear implant is a device that provides electrical stimulation to the auditory nerve. A cochlear implant is indicated for patients with severe-profound sensorineural hearing loss, bilaterally, and who receive limited benefit with hearing aids. In cases of sensorineural hearing loss there is damage to the hair cells in the cochlea. This damage prevents sound effectively transmitting to the auditory nerve. With a cochlear implant, the damaged hair cells are bypassed and the auditory nerve is directly stimulated. Cochlear implants are FDA approved for patients as young as 12 months. Cochlear implant candidacy is determined by the Tripler Cochlear Implant Team.
Dizziness and Balance Disorders
The term dizziness is used to describe a wide variety of symptoms including lightheadedness, spinning, floating, unsteadiness and imbalance. There are many causes of dizziness and imbalance, including disorders of the vestibular system. The vestibular system includes the balance organs of the inner ear, nerve, and pathways in the brainstem and cerebellum.
Videonystagmography (VNG)/ Electronystagmography (ENG): is the most commonly used test to evaluate the vestibular system. When the head is in motion, the inner ear balance organs send signals to the eye muscles to keep vision in focus. Eye movements are recorded, either by infrared video or with electrodes to evaluate this interaction.
Posturography: evaluates the interrelationship of three parts of the balance system. In a normal system, balance is accomplished with the teamwork of vision, proprioception (sensors in muscles and joints) and the vestibular system (balance portions of the inner ear and brain).This test assesses which parts of the balance system the patient relies on and which parts may be problematic for the patient. Posturography results should be interpreted in conjunction with the results of other vestibular tests.
Rotary Chair Testing: provides more information in assessing inner ear function. The patient sits in a chair, in a small dark booth. Electrodes or video goggles are used to record eye movements, while the chair is rotated back and forth at different acceleration rates. Rotary chair testing is particularly useful when confirming a suspected loss of inner ear balance function in both ears and determining residual function.
Results from vestibular
function testing are used to determine which part(s) of the vestibular
and balance system is affected. Some balance disorders can be treated
with a vestibular rehabilitation program with a trained provider, while
other problems are managed medically.