Comprehensive Assessment and Evaluation of Hearing Loss

With conductive hearing loss, the sensory organs of the inner ear remain intact, so hearing challenges usually involve loudness issues due to the failure of sound waves to penetrate through the obstruction rather than problems with sound clarity. An obstruction in the ear canal may be caused by:

• Narrowing of the ear canal
• Too much earwax or foreign substances in the ear
• Exostoses (bone-like protrusions inside the ear canal)
• Otitis externa (swimmer’s ear)
• Microtia or atresia (congenital deformities)

The cause of an obstruction in the middle ear might include:

• Ruptured tympanic membrane (eardrum)
• Tympanosclerosis (thickening of the tympanic membrane)
• Fluid in the ear or otitis media (ear infection)
• Eustachian tube blockage
• Otosclerosis (affects the stapes bone in the middle ear)
• Abnormal growths or tumors
• Ossicular discontinuity (broken connection between the bones of the middle ear)

Sensorineural hearing loss is the most common type of permanent hearing loss that results from damage to the tiny hair-like cells of the inner ear (stereocilia) or the auditory nerves that transfer sound signals to the brain.

Sensorineural hearing loss can be the result of a genetic syndrome or an infection passed from mother to fetus, but the majority of sensorineural hearing loss cases develop later in life (presbycusis, or age-related hearing loss) or from ongoing exposure to loud noise (noise-induced hearing loss or NIHL).

In addition to reduced hearing clarity, characteristics of sensorineural hearing loss can include feelings of unsteadiness or dizziness, tinnitus, and early onset dementia or cognitive decline. Causes of sensorineural hearing loss may include:

• Heart disease and diabetes
• Infections such as mumps
• Meniere’s disease
• Use of ototoxic drugs or medications
• Acoustic neuroma or a cancerous growth in the inner ear
• Concussion or traumatic brain injury
• Autoimmune diseases or thyroid disease

Mixed hearing loss is a combination of sensorineural and conductive hearing loss in which either sensorineural or conductive hearing loss is already present before the other condition develops. Those experiencing a mixed hearing loss will struggle with clarity and loudness issues related to both types of hearing loss.

The most common circumstances associated with mixed hearing loss include:

• A form of trauma that leads to conductive hearing loss in a person with a sensorineural hearing loss
• Someone already experiencing conductive hearing loss developing a sensorineural hearing loss as they age
• Blast injuries and various traumas, which can cause concurrent sensorineural and conductive hearing loss

Some forms of conductive hearing loss can go away as inflammation decreases, either on its own or thanks to a medical intervention, or when an obstruction in the ear canal either comes out on its own or is removed by a hearing care professional.

Most comprehensive hearing assessments take no more than 30 minutes to complete, although the intake process and the discussion of your results at the end of testing can take up additional time.

The diagnosis of hearing loss typically includes a series of tests that may or may not include:

Tympanometry
A tympanometry measures the reaction of the eardrum to a subtle pressure change in the ear canal. This test may help identify the presence of fluid behind the eardrum, a ruptured eardrum, or other middle ear issues.

Pure Tone Audiometry
A pure tone audiometry helps determine the type and severity of your hearing loss by establishing your hearing threshold, the lowest level at which you can hear pure tones transmitting through headphones at descending levels from 250 Hz-8000 Hz.

Speech Audiometry
Your speech reception threshold (SRT), the first of two speech audiometry tests, establishes the low-end threshold of speech reception by presenting spondee words (composed of two syllables pronounced with equal stress and effort) in descending levels and measuring your responses.

The second type of speech audiometry is a speech discrimination score, a calculated percentage of the number of phonetically-balanced words you can repeat correctly at a comfortable listening level.

Bone Conduction Test
Bone conduction testing transmits sound signals directly to the inner ear through the surrounding bones by using a special type of headband. By bypassing the normal hearing pathway, we can compare pure tone test results and bone conduction test results to distinguish between sensorineural or conductive type hearing loss.

Additional Tests
Your audiologist might decide to conduct additional tests like an otoacoustic emissions test (OAEs), which measures how the nerve cells in the cochlea react to the presence of sounds, or an auditory brainstem response test (ABR), often used with children or others who are unable to complete a typical hearing screening, which helps identify hearing loss issues related to the brain or along a brain pathway.