Hearing Loss

What is Hearing Loss?

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Ear Anatomy

The anatomy of the ear is often categorized into three different parts: Outer, Middle, & Inner Ear

Outer Ear
The outer ear consists of the auricle (pinna) and the external auditory meatus (ear canal).  The purpose of the outer ear is to collect, funnel, and amplify sound for the middle ear. 

  • Auricle (pinna) – visible part of the outer ear.
  • External Auditory meatus (ear canal) – tube through which the sound gets funneled into and travels towards the tympanic membrane (ear drum)

Middle Ear
The middle ear consists of the tympanic membrane (ear drum), middle ear ossicles (3 bones), eustachian tube, and tympanic cavity (middle ear space).  The purposes of the middle ear include: 1) transfer air pressure waves into mechanical vibrations that are then transferred into hydraulic vibrations within the cochlea, and 2) Equalizing the pressure in your middle ear to the atmospheric pressure via the proper opening and closing of the Eustachian tube.

  • Tympanic Membrane (ear drum) – an oval, thin, membrane that translates the air pressure waves and converts them to vibrations for the middle ear ossicles.
  • Middle ear ossicles (Bones) – the malleus, incus, and stapes, often referred to as the hammer, anvil, and stirrup, respectively, take the vibration from the ear drum and transmit this sound into the perilymph of the cochlea (inner ear) by displacing the oval window.  This bone conductivity amplifies the sound wave 10 times before it reaches the cochlea.
  • Eustachian Tube – is the canal that connects the middle ear cavity with the nasopharyngeal region (back of the nose and throat) and is responsible for equalizing the pressure of the middle ear space to the atmospheric pressure.  
  • Tympanic Cavity (middle ear space) – is the space that houses the middle ear ossicles, important musculature and tendons.

Inner Ear
The inner ear consists of the Cochlea, Semi-Circular Canals, and Vestibule.  The primary purpose of the inner ear is to conduct sound to the central nervous system (CNS) as well as to assist in balance function.

  • Cochlea – is the snail-like shell that is encased in bone and is the essential organ of hearing.  The cochlea converts the hydraulic pressure into frequency specific information for the brain to convert as sound.
  • Semi-Circular Canals – are the three canals that are oriented perpendicular from each other to provide a 3 dimensional plane to detect angular acceleration of the head which is crucial for maintaining balance.
  • Vestibule – is the central part of the bony labyrinth that houses certain organs that help detect vertical and horizontal acceleration of the head which also assists in maintaining balance.

 

Hearing Loss

A survey (MarkeTrak 2004) estimated that nearly 10% of the US population, or 32 million people, have a hearing difficulty.  Here are more general statistics on the incidence and prevalence of hearing loss:

  • 3 in 10 individuals over 60 years of age have hearing loss
  • 1 in 6 baby boomers (41 – 59 years of age) have a hearing problem
  • 1 in 14 Generation Xers (29-40 years of age) already have a hearing loss
  • At least 1.4 million children that are 18 or younger hearing hearing loss
  • Estimates show that 3 in 1,000 babies are born with serious to profound hearing loss

What causes hearing loss?

Any detriment to the Outer, Middle, and Inner Ear could potential cause a hearing deficit.  Some Causes of hearing loss include:

  • Damage to the Cochlea.  Aging, noise exposure, ototoxic medications, poor diet, viral infections can all compromise the efficiency, sensitivity and structural composition of the cochlear labyrinth. 
  • Ear Infections
  • Tumors
  • Eardrum perforations
  • Syndromes
  • Obstructed ear canal (wax build-up, foreign body, etc)
  • Malformations of the ear
  • Physical trauma
  • Hereditary causes

How do you prevent hearing loss?

Presbycusis refers to the hearing loss as a result of the natural aging process.
Acquired hearing loss refers to any deterioration of hearing as a result of environmental factors excluding aging (i.e. ototoxic medication, noise exposure, viral causes of hearing loss, etc)

  • Protect Your hearing
  • Limit exposure to loud sounds (i.e. music, noise, etc.)
  • Review your medications for ototoxicity (review the list with your physician or audiologist for medications that could damage your hearing)
  • Maintain healthy ear hygiene (clean your ears properly)
  • Eat healthy foods (your diet provides the nutrients that your ear needs to stay healthy)
  • Test your hearing

For many, hearing loss can be mitigated or avoided.  For instance, Noise induced hearing loss is completely preventable.  Reducing the volume and time exposed to loud sounds, in conjunction with using hearing protection when around noisy environments, can effectively prevent you from experiencing noise induced hearing loss.