How Hearing Works

The human ear has three parts: the outer ear, middle ear and inner ear. 

The outer ear, the pinna, has a number of curves and points slightly forward.  It is positioned and structured to efficiently direct sound waves (vibrations) down the ear canal where they interact with the eardrum.  The tympanic membrane, commonly called the eardrum, separates the ear canal from the middle ear. 

As sound waves strike against the eardrum it vibrates.  Higher-pitched sound waves move the eardrum rapidly, and louder sound moves the eardrum a greater distance.  The vibrations are then passed to the three small bones of the middle ear, the malleus, the incus and the stapes (or the hammer, the anvil and the stirrup), where the bones amplify the force (pressure) from the eardrum further and transfer the vibrations to the cochlea in the inner ear.  As the waves move across the hair cells of the cochlear membrane, they send electrical impulses to the cochlear nerve and on to the brain.  The brain interprets the impulses as sound (music, voice, a car horn, etc.).

Hearing Loss

There are two types of hearing loss: "Nerve" hearing loss and "Mechanical" hearing loss.

Nerve Hearing Loss (Sensorineural)

Sensorineural, or “nerve” hearing loss arises when the auditory nerve is not working properly.  This can be caused by many things, including genetics, age, noise exposure, medications, chemotherapy, and other unknown culprits.  This type of hearing loss can be stable or progressive, especially with continued exposure to the causative agent.  Unfortunately, the auditory nerve cannot be repaired but sensorineural hearing loss can often be helped with hearing aids; and in extreme situations, with implantable hearing devices.

Mechanical Hearing Loss (Conductive)

Conductive, or “mechanical” hearing loss occurs when there is a problem getting sound to the inner ear and the auditory nerve. Sound waves travel through the ear canal and cause the eardrum to vibrate. This in turn causes the bones of the middle ear to move and stimulate the inner ear.  Earwax, infection, a perforated eardrum, fluid behind the eardrum, and problems with the hearing bones can all interrupt the transmission of sound waves as they travel to the inner ear.  Most conductive hearing losses can be treated with medication or by surgery.

Testing for Hearing Loss

South Texas ENT offers a full range of auditory services, including complete hearing exams, pediatric hearing evaluations and hearing aid services performed by licensed audiologists and certified OtoTechs.

Diagnostic Audiology Testing Services

  • Behavioral pure tone audiometry and speech discrimination testing
  • Play audiometry
  • Tympanometry
  • Eustachian tube function testing
  • Otoacoustic emissions testing (OAE)
  • Electronystagmography (ENG) / Videonystagmography (VNG)

Other Hearing and Ear Services

  • Custom hearing protection for hunters and shooters
  • Custom ear molds for portable headphones
  • Custom swim molds to keep water out of ears

 

 

American Academy of Otolaryngology

For more information on these and other ENT conditions visit the American Academy of Otolaryngology’s website. http://www.entnet.org/HealthInformation

 

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