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A Deep Understanding and Diagnosing Hearing Loss. How it Occurs with Aging?

Deep knowledge about the science of hearing and hearing loss.

Imagine sitting in the cafe with your favorite coffee in hand. The subtle click of mugs and murmur of people around you make it more scenic. But you are finding it difficult to understand what your friend across the room does not understand.

So, it is very common for people to have their hearing ability affected at any point in their lives.

Hearing loss, which affects millions of individuals worldwide, may have a devastating impact on daily life. To maintain one’s quality of life, one must understand what causes it and develop effective ways to deal with it.  Our article is all about how hearing impairment can occur and affect our lives.

But let’s first understand the science of hearing.

Science of Hearing

Hearing is one of the five common human senses we have.  To understand how we hear and feel the world around us, we need to know how the ear works and how it is structured. The ear has three parts: the outer, middle, and inner ears.

All of the parts serve different purposes.

External Ear
The first stop on the sound journey is the external ear, which is the visible part seen with the eyes. It includes the pinna (or auricle) and the external auditory canal. The function of the pinna is to receive sound waves from the environment and direct them to the eardrum via the auditory canal.

Middle Ear

The middle ear is a small, air-filled cavity. The eardrum, also known as the tympanic membrane, divides the middle ear from the outer ear. It is connected to the inner ear through three tiny bones known as the malleus (hammer), incus (anvil), and stapes (stirrup). The malleus receives vibrational energy from sound waves and relays it to the incus. The stapes receive these vibrations from the incus. The technique of sequential engagement enhances and transmits the vibrations of sound to the inner ear, allowing for exact auditory awareness.

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Inner Ear

The inner ear is home to the semicircular tubes, vestibule, and cochlea. The cochlea, an organ with a spiral structure, is essential for converting sound waves into electrical impulses. It contains hair cells, which change direction in response to fluid motion and initiate the conversion of these mechanical movements into nerve signals. After that, the hearing nerve sends impulses to the brain, enabling us to understand sounds. The vestibule and semicircular canals are vital for balance and spatial awareness, even though they do not directly aid in hearing.

The Hearing Process

The hearing process is complex, and the above parts of your auditory system are essential to hearing. The following steps are part of the hearing process.

  1. The eardrum moves in response to sound waves that enter the ear canal.
  2. When exposed to various sounds, the eardrum will vibrate.
  3. The ossicles are the channels by which sound vibrations go to the cochlea.
  4. The fluid inside the cochlea vibrates when sound enters it, much like ocean waves do.
  5. The fluid’s movement then moves the hair cells. If the hair cells generate any neurological signal, the auditory nerve will pick it up. One set of hair cells in the cochlea transmits information about low-pitched sounds, whereas the other set transmits information about high-pitched sounds.
  6. Signals are transmitted from the auditory nerve to the brain and converted into meaningful and recognizable sounds.

The way our ears work ties us to the sounds around us. The amazing thing about our hearing is that it lets us pick out and understand the tiniest sounds. The neural counterparts of sounds like music, words, danger, and environmental sounds can be stored in our brains. This connection makes it much easier for us to recognize and understand new and old sounds.

Given the complicated, multi-step process that permits people to hear. Surprisingly, things occasionally go wrong, and hearing can be affected.

Understanding Hearing Loss

Hearing loss, impaired hearing, or deafness is the inability to hear sounds. Hearing normal sounds like speech becomes tough, if not impossible. It is the third-most chronic disease in the world, and in the US, around 15% of adults report having some noticeable hearing loss.

Hearing loss can manifest in various forms, such as sensorineural, conductive, or mixed types. It ranges from mild difficulties catching words, especially against background noises, to a complete inability to hear. Identifying the type is crucial in determining the right course of action.

Hearing Loss Vs. Deafness

Deafness, profound deafness, and hearing loss are separate yet interconnected conditions, each possessing distinctive characteristics and symptoms. A small table summarizes all the details of it.

Aspect Deafness Hearing Loss Profound Deafness
Definition A partial or total inability to hear. A decline in hearing capacity. An extreme or total loss of hearing.
Severity It may be mild or highly significant. Ranges from mild to severe. Consistently severe to total loss.
Communication People suffering may use lip reading or other visual communication methods. Affected people use hearing aids, cochlear implants, or other assistive devices. Rely on sign language and visual communication aids.
Causes Genetic factors, aging, exposure to loud noise, illness, etc. It includes aging, noise exposure, and infections. Usually caused by genetic factors or severe damage to the auditory system.
Diagnosis Audiometric tests to determine the level of hearing loss. It is the same as deafness, focusing on the degree of hearing impairment. Audiometric tests confirm the profound loss of hearing.

Causes and Types of Hearing Loss

Prolonged or repeated exposure to decibel levels of 85dB or higher may lead to hearing damage.

According to the American Speech-Language-Hearing Association (ASHA), hearing loss has three main categories, each with its own causes.

The three most prevalent types of hearing loss are mixed hearing loss, conductive hearing loss, and sensorineural hearing loss (SNHL).

1. Conductive Hearing Loss

A condition known as conductive hearing loss develops when vibrations in the external auditory canal cannot reach the eardrum and middle ear bones. Soft or muted sounds may become inaudible to individuals as this form of hearing loss develops.

Causes: As per the American Speech-Language-Hearing Association (ASHA), several potential causes exist, such as a damaged eardrum, excessive earwax trapped in the ear canal, or an ear infection. Some other possible reasons for hearing loss include benign tumors, scarring of the ear canal from repeated infections, and foreign objects caught in the ear.

Symptoms: Conductive hearing loss symptoms could differ according to the condition’s origin and degree. But some common ones include:

  • Sudden or abrupt loss of hearing
  • Dizziness
  • Reduced hearing
  • A full or “stuffy” sound when heard
  • Draining of the ear
  • Pain and tenderness in the ear

In rare cases, medical or surgical interventions can restore normal hearing.

2. Sensorineural Hearing Loss (SNHL)

Sensorineural hearing loss (SNHL) occurs when there is harm to the structures within the inner ear or to the nerve pathways leading to the brain. It is also known as nerve-related hearing loss. According to estimates, about 30 million Americans aged 12 and up suffer from sensorineural hearing loss.

Causes: It is not due to common ear issues like infections, earwax buildup, or foreign objects in the ear canal. Aging, congenital malformations such as Meniere’s disease, inner ear infections (such as mumps, meningitis, or scarlet fever), and head trauma are the leading causes of sensorineural hearing disorders.

Symptoms: Some of the most common symptoms include

  • Tinnitus ( ringing in ears)
  • Difficulty hearing noises in the presence of background noise.
  • Particularly difficulties interpreting children’s and female voices. Even clear, regular, or loud noises might seem muted or indistinct with SNHL.
  • Dizziness or balance issues
  • Difficulty hearing high-pitched noises
  • Sounds and speech appear muffled, as if you can hear but not comprehend them.

This hearing loss frequently lasts a lifetime and varies with its severity.

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3. Mixed Hearing Disorder

Mixed hearing loss arises from a combination of sensorineural damage in the inner ear (cochlea) or auditory nerve and conductive damage in the outer or middle ear.

Cause: Injuries to the ear canal are a leading cause of mixed hearing loss. For instance, a person whose conductive hearing loss has been present for some time may develop age-related hearing loss as they age. On the other hand, wax impaction can cause transient mixed hearing loss in people with age-related hearing loss. Damage to the auditory nerve, whether sensorineural or conductive, can result from blast injuries and other forms of trauma.

Symptoms: Mixed type of hearing loss include

  • The inability to understand words
  • Preferred to listen to loud noises on TV
  • Frequent ear infections
  • Preferring to hear from one ear at a time.

4. Presbycusis

Presbycusis is the term used to describe bilateral, age-related hearing loss. It literally means “old hearing” or “elder hearing” and impacts over half of all adults aged 75 and above and one-third of all individuals aged 65 and up.

More than half of those over 75 in the United States have some age-related hearing loss.  

Causes: Hearing loss associated with aging can have several reasons. Changes in the middle and inner ear, nerve changes that supply the brain, loud noises, medical conditions, and certain medications may play a role.

Symptoms: The following are the symptoms of hearing loss.

  • A symptom of presbycusis is a diminished ability to hear or withstand loud noises.
  • Inability to understand words in loud noises
  • Not being able to understand the sounds of “s” and “th”
  • Mumbled and slurred speech by the affected person.
  • One or both ears might also experience tinnitus, often called ear ringing.

Other forms of hearing loss that affect a small number of people are:

While some forms of hearing loss are temporary, others do not improve with time.

Levels of Hearing Loss

Hearing loss can be classified into five distinct levels: profound, moderate, moderately severe, severe, and minimal.

https://www.researchgate.net/figure/The-audiogram-sample-defining-various-types-of-hearing-loss-constructed-on-the-basis-of_fig3_343674204
Image source: https://www.researchgate.net/figure/The-audiogram-sample-defining-various-types-of-hearing-loss-constructed-on-the-basis-of_fig3_343674204
  • Mild hearing loss, ranging from 26 to 40 decibels, is frequently characterized by the inability to perceive low-pitched noises. Frequently, these noises consist of leaves rustling, birds chirping, or the refrigerator whirring. A person with mild hearing loss frequently experiences difficulty hearing speech in cluttered environments.
  • Moderate hearing loss, ranging from 41 to 55dB, is characterized by impaired perception of moderately strong sounds, specifically those below 41 dB. Individuals may experience challenges when it comes to pronouncing speech sounds, particularly those with higher frequencies such as /f/, /s/, and /th/.
  • Moderately severe hearing loss (56-70dB) is characterized by the inability to hear even normal conversations in silence unless the individual being addressed raises their voice. Difficulties in noisy environments and groups continue to intensify, given that this group can no longer distinguish sounds below the threshold of normal conversation.
  • Severe hearing loss, ranging from 71dB to 90dB, establishes an imperceptible barrier to communication. Severe hearing loss renders speech sounds undetectable unless generated at an exceptionally high volume. Following and listening in on a group discussion is often difficult, requiring considerable effort. Individuals with this form of hearing impairment are currently incapable of perceiving sounds generated below 71 dB.
  • Profound hearing loss (91dB or greater): Although it is still possible to perceive some harsh sounds, even with increased effort, communication becomes unattainable. Individuals with this form of auditory impairment cannot perceive sounds generated below 91dB.

Diagnosing Hearing Loss

Identifying what part of the hearing system has problems is the initial step in enhancing one’s health and quality of life when confronted with hearing difficulties.

The diagnostic process entails an array of examinations audiologists carry, including tympanometry and audiometric tests. These examinations aid in determining the nature and severity of hearing impairment, thus laying the groundwork for an efficacious therapeutic regimen. It is vital to obtain an accurate diagnosis to manage hearing loss effectively.

The following is a breakdown of the most common test types and the hearing loss condition they can assist in diagnosing:

1. Physical Examination.

A doctor will examine the ear canal to rule out infections and earwax, two potential causes of hearing impairment. Additionally, the shape of your ear might be a contributing factor in hearing loss.

Doctors look at your medical history to understand what’s causing your hearing loss. They question the onset of symptoms, the severity of the loss of hearing (in one or both ears), and whether or not your occupation exposes you to loud noise. Additionally, they could ask whether you have a family history of hearing loss or any other medical issues, such as recurrent ear infections, and what drugs you use.

2. Pure-Tone Testing.

The gold standard in hearing tests, pure-tone testing, determines how well an individual can perceive the lowest possible sound volume. During the test, an audiometer plays noises into the subject’s ears at different levels and frequencies. An audiogram graphically displays the findings and can aid in determining the severity and kind of hearing loss (conductive, sensorineural, or mixed).

3. Speech Testing.

The speech test measures the individual’s speech comprehension and auditory perception. By having the individual repeat words spoken at varying decibels, it will be possible to determine the precise threshold at which speech becomes incomprehensible.

4. Middle Ear Tests

Acoustic reflex testing and tympanometry are two of them. Tympanometry is useful when diagnosing issues with the middle ear because it detects how the eardrum moves in reaction to air pressure. When the patient is subjected to loud noises, an acoustic reflex test can uncover problems with the auditory nerve or its passage to the brain by measuring the contractions of the middle ear muscles.

5. Otoacoustic Emissions (OAEs)

If a patient’s medical history and physical examination point to sensorineural hearing difficulties, an otoacoustic emission test (OAE) can be administered by audiologists to check for damage to the cochlea, the inner ear.

To conduct an OAE test, a small probe fitted with a speaker and microphone is inserted into the ear canal. A person with hearing loss may not create or have diminished sound waves in their inner ear, which the test detects.

6. Bone Conduction Testing. 

The specific kinds of hearing changes can be better identified using the bone conduction test. By positioning a bone vibrator behind the ear, it is possible to avoid the middle ear and send sound waves straight to the inner ear. This test can distinguish between sensorineural and conductive hearing loss.

7. Radiological Examinations

Suppose hearing tests reveal that symptoms may be attributable to conductive hearing loss. In that case, medical professionals may advise the utilization of a computed tomography (CT) scan to obtain a more precise image of the middle ear. Similarly, the doctor may suggest an MRI for unilateral hearing inability to rule out the causes better.

Whether someone has conductive, sensorineural, or mixed hearing impairment depends on the results of a series of tests examining a distinct part of the auditory system. It’s worth noting that specific tests may differ from one patient to another according to factors including age, symptoms, and medical history.

8. App-Based Hearing Tests

Several hearing test apps for iPhone and Android provide different features and evaluation methods. Such as the Mimi Hearing Test, uHear, HearingTest.Online, and Check Hearing.

It is recommended that you take tests from various sources, such as an online tool that measures your speech comprehension and another that evaluates your hearing across many frequencies.

The complicated nature of hearing, the many types of hearing loss, and the diagnostic procedures all provide a vivid picture of the challenges and impacts of hearing loss.  Now that we’ve covered the many kinds of hearing loss and their causes, it’s time to move on to the next important step: treatment. There is a lot of optimism and potential on the road from diagnosis to therapy, which is all covered in our article here.

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Dr Aimen

Being a Doctor by profession, Aimen is passionate about helping people get better health in their lives. Aimen enjoys her research on Prime With Time subjects and strives to create better awareness of the problems and changes related to women's health.
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