How We Hear

Physiology of Healthy Auditory (Hearing) System

Sound wave travels to the ear (what you see) and is delivered 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. Then most complex of all sensory pathways, the auditory nervous system processes and transmits/receives. sounds from and to inner ear to/from 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) or bilateral (both) ear(s)

  • 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 on the negative effect of hearing loss, over 63 percent of adults aged 70 years and older in the U.S. population  has 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 of three) are neglecting something is very crucial for their health.

Risk Factors

Auditory system is very delicate, complex, and susceptible.

Some of definite risk factors are, loud noise exposure via shooting, mechanic, factory, motors, or loud music, head or neck trauma and injury, age, otosclerosis, ear infections/inflammation, ototoxic drugs, or Meniere's disease.
Possible risk factors are familial inheritance, geographic region, health status -fair or poor, low socioeconomic status, or smoking.

Health Risk Related to Hearing Loss

Impact of Untreated Hearing Loss

Many researchers have reported the hearing loss is linked 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 first seeing audiologists might benefit you? 

Because the profession is medically trained to diagnose hearing loss -the degree, cause- and recommended 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 the findings. In this way, you might save time and resources during the process of diagnosing and planning a treatment plan.  Because all other professions would need results of hearing tests that assist them to diagnose.    

In most retail stores- including Costco, Sam's Club, etc. - there is no audiologist but you may see a hearing instrument specialist (HIS). There are many different names - that all are referred as hearing care  professionals. They are certified and licensed to dispense hearing aids legally.  However, the requirement to be licensed in most states are very loose in their education requirement and a clinical training.  Many times their training is more focused on sales. 

It is your choice to choose your hearing care professional wisely and medical fields would recommend that your initial diagnose to be done by a medical profession not the sales personal.  Anything short of "the best fit" may worsen your auditory system.

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 comfortable level, and that causes stress on one's vocal cord and causes frustration or tiredness.

  • Repetition, sometimes several times, is usually required.

  • Loud TV volume can bother others, especially more to those whose hearing is sensitive to loud sound.

  • Learn communication strategies together with your friends and family.

Hearing Conservation/Protection

It is the best strategy!

One of most hazardous causes of hearing loss but 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 Standard and every work place is required to comply.
NIHL also occurs via recreational loud noise such as shooting, power saws, snow mobile, loud music etc.
Continuous exposure is more damaging than intermittent. The break between exposures tends to give rest in the auditory system and recovers shifted hearing due to noise.
To reduce the intensity, wear personal hearing protector. Investing to protect when they are healthy is much more beneficial than trying to compensate after loss occurs.  The outcome is not comparable.
Get a baseline audiogram and observe annually if you are involved in a very noisy environment either via occupational or recreational.
Get a professional advise and custom hearing protection and educated for better motivation.