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How We Hear

Physiology of a Healthy Auditory (Hearing) System


Sound waves travel to the ear and is delivered to the ear drum through a narrow tunnel. We hear when vibrations (sound waves) reach our auditory system (hearing structure)

The ear consists of three parts: the outer ear, the middle ear, and the inner ear. The most complex of all sensory pathways, the auditory nervous system processes and transmits sounds. This system receives sounds from the inner ear to the central nervous system (brain).

 

Hearing Loss (HL)

Classified by several different categories

  • Site -Conductive hearing loss or sensorineural hearing loss; peripheral hearing loss or central hearing loss

  • Degree - slight, mild, moderate, moderately severe, severe, or profound/deafness

  • Number -unilateral (one ear) or bilateral (both ears)

  • Cause - Noise-Induced hearing loss (NIHL)-occupational or recreational, Age-related hearing loss (ARHL or presbycusis), hereditary HL (genetic disposition or genetic susceptibility), infections, toxicity, otosclerosis, tumor, labyrinthitis, trauma, head injury, cerumen impaction etc.

  • Time of onset- Congenital (present at birth), acquired, gradual, sudden etc.

Hearing Loss in Early Childhood

It is imperative to test hearing in neonates and ANY hearing loss detected needs to be compensated.

As we learn more about physiology of hearing and pathophysiology of hearing loss, the evidence has shown the function of the auditory nervous system can change without any detectable changes in morphology due to neural plasticity. This means that the function of specific parts of the nervous system change more or less permanently depending on how they are activated.  

Sound deprivation from either conductive hearing loss or sensorineural hearing loss can severely affect the normal development of the auditory nervous system during childhood and even on the function of mature nervous system.

Development of the auditory nervous system depends on appropriate stimulation early in life.  Deficits from insufficient stimulation during development is not reversible.

Hearing Loss In Adults

More adults than we think are Underdiagnosed & Undertreated

Plasticity of the auditory nervous system manifests in many forms and can be compensatory and harmful.  Studies of mice indicate that appropriate sound stimulation can slow the progression of age-related hearing loss (ARHL, presbycusis).  Like untreated hearing loss in early childhood, prolonged hearing loss in adults is not reversible. 


Despite the rising concern over the negative effects of hearing loss, over 63 percent of adults aged 70 years and older in the U.S. population has a hearing problem using the definition of hearing loss  (>20 dB) by the World Health Organization (WHO) according to Institute on Deafness and Other Communication disorders (NIDCD). Furthermore, only fewer than 30 percent of those who could benefit from hearing aids has ever used them. That means 70 percent ( two out of three persons) are neglecting something that is crucial to their health.

Risk Factors

Our Auditory system is very delicate, complex, and susceptible.

Some definite risk factors are, loud noise exposure via gun shooting, working as a mechanic, in a factory, being around loud machinery or motors, or loud music, head or neck trauma and/or injury, age, otosclerosis, ear infections/inflammation, ototoxic drugs, or Meniere's disease.
Other possible risk factors include familial inheritance, geographic region, health status -fair or poor, low socio-economic status, or smoking.

Health Risk Related to Hearing Loss

Impact of Untreated Hearing Loss

Many researchers have reported that hearing loss is linked to other medical conditions, such as cognitive decline/dementia, Alzheimer's disease, social isolation, loneliness, depression, increased falls, cardiovascular disease, diabetes, and mortality.

The First Step For a Hearing Concern

Why is it best to see an Audiologist first? 

Because their profession is medically trained to diagnose hearing loss - the degree, cause - and recommending the right treatment solutions for each patient. They are also trained to treat functional disorders of hearing when it is not medically treatable. 

Audiologists may refer you to a general ENT, otologist, or neurotologist for medical or surgical options or to your primary care physicians (PCP) for further differential diagnosis, depending on their findings. In this way, you might save time and resources during the process of diagnosing and starting a treatment plan, as the other professions would need the results of your hearing tests to assist them in their diagnosis.    

In most retail stores- and warehouse clubs like Costco, Sam's Club, etc. - there is typically no Audiologist, but you may see a hearing instrument specialist (HIS). They are referred as being hearing care professionals (HCP), certified and licensed to dispense hearing aids legally. However, the requirement to be licensed in Florida is a 6 month process to be "certified". The feedback we have received from clients has been that they felt their interactions were more "sales focused" than patient centered, as you would hope to  expect from a doctor/patient relationship. 


Choose your hearing care professional wisely...most medical professionals would recommend that your initial testing and diagnosis should be done by an Audiologist, not a sales professional.  Anything short of "the best possible fit" may worsen your auditory system and hearing.

Hearing Care is Caring for Your Loved Ones.

Hearing loss may impose difficulty on your friends and family.

  • In conversation with a person with hearing loss, people might have to speak louder than their usual comfort level, and that causes stress on one's vocal chords and can cause frustration and/or tiredness.

  • Repetition, sometimes several times, is usually required.

  • Loud TV volume can be annoying and bothersome to others, especially if they are sensitive to loud noise.

  • Learn communication strategies together with your friends and family.

Hearing Conservation/Protection

It is the best strategy!

One of the most hazardous causes of hearing loss that is also preventable is noise exposure.  The extent of damage from noise exposure varies depending mainly on the intensity of the noise and duration of the exposure.  The Occupational Safety and Health Administration (OSHA) regulates noise standards, and every work place is required to comply.  Noise induced hearing loss (NIHL) also occurs via recreational loud noises such as gun shooting, power saws, snow mobiles, loud music etc.

Continuous exposure is more damaging than intermittent exposure. The break between exposures tends to give rest to the auditory system and recovers shifted hearing due to noise.

To reduce the intensity, wear personal hearing protection. Investing to protect your hearing is more beneficial than trying to compensate after hearing loss occurs.  The outcome is not comparable. Get a baseline audiogram and repeat it annually if you are involved in a very noisy environment either via occupation or recreational exposure. Get professional advice and custom hearing protection.