What Is Hearing Loss?

An experienced and measured decrease in hearing acuity levels, resulting in different degrees of impaired communication. It is commonly perceived by the listener as lowered volumes.

However, it also can start off as just word confusion. It occurs when there’s a problem with one or more parts of one ear or both ears.

Types of Hearing Loss

1. Conductive Hearing Loss

The Outer Ear picks up sound waves and the waves then travel through the outer ear canal to hit the eardrum. When there is a problem with a part of the outer ear that blocks sound from going to the middle ear, most commonly impacted wax, it results in a conductive hearing loss and is always reversible.

Sound waves hit the eardrum in the Middle Ear, and cause the eardrum to vibrate, corresponding to the intensity of the sound. This vibration moves three tiny bones/ossicular chains in the ear, called the hammer/malleus, anvil/incus and stirrup/stapes. They help sound move along into the inner ear.

A problem with the middle ear, that affects the movement of sound in the form of mechanical vibrations along with the eardrum and the ossicular chain will result in a conductive hearing loss. It may or may not be reversible to some extent.

2. Sensorineural Hearing Loss

Vibrations then travel to the Inner Ear/Cochlea. The cochlea is filled with liquid and lined with cells called the hair cells (the outer and inner cells). The sound vibrations make the hair cells move and transduce these mechanical vibrations to chemical changes in the cell that further cause electrochemical changes in the nerve supply to the cochlea. This electrochemical change that occurs is how sound is transduced and sent to the brain for further processing and thus is how hearing takes place.

A problem in the inner ear or the nerve from the inner ear to the brain can cause sensorineural hearing loss and is almost always permanent.

 

3. Mixed Hearing Loss

Affect or damage to the outer and/or middle ear and the inner ear will cause mixed hearing loss which has both a conductive and a sensorineural component.

Other Types of Hearing Loss/Impairment

Auditory dys-synchrony: When hearing acuity is normal or varies with time, however, with an almost constant adverse effect on understanding auditory stimuli (especially speech). The site of the issue is the auditory nerve.

Central Auditory Processing Disorder: Hearing acuity is normal but speech understanding is affected (particularly in adverse listening conditions). The site of issue starts at the brainstem level and can include or be anywhere up to the cortex of the brain responsible for processing sound stimuli.

What tests do I have to undergo for diagnosing hearing loss?

 

AUDIOMETRY – The “Gold standard” hearing test.

 

Hearing loss/acuity is measured using a simple test called Audiometry. It usually is completed within 10-15 minutes (sometimes longer if speech hearing thresholds are also to be evaluated).

This is a test that measures the lowest hearing levels for tones from 250Hz to 8KHz. This range of frequencies is taken since the frequencies corresponding to speech occur in this range.

The degrees of hearing loss are decided based of the results of the audiometry test and the graph handed over to you is called your Audiogram.

Degrees of hearing loss

These are the probable results of your audiogram;

1. Normal Hearing Sensitivity.
2. Minimal Hearing Loss.
3. Mild Hearing Loss.
4. Moderate Hearing Loss.
5. Moderately-severe Hearing Loss.
6. Severe Hearing Loss.
7. Profound Hearing Loss.

 

**You may even see a comment like sloping mild to moderate hearing loss, that only means you have better low-frequency hearing. A comment like reverse sloping moderately to mild hearing loss would mean you have better hearing in the higher frequencies.

 

The degree will always be followed by the type of hearing loss (conductive, sensorineural or mixed) e.g., moderate mixed hearing loss. This is why the test is done first with headphones and then with a headband that fits firmly to the head called the Bone Vibrator. Ensure this part of your test is done to give you the complete picture of your hearing loss (if you do have a hearing loss).

 

Issues with communication start with the mild hearing loss itself.

 

What other tests will/might I be asked to undergo?

In the case your audiologist or ENT deems it necessary, they may ask you to go in for:

• Tympanometry (that tests the middle ear).
• Reflectometry (tests the middle ear and the nerve pathways).
• Speech hearing thresholds and word recognition scores.
• Electroacoustic tests (ABR, MLR, LLR etc.) [when these are asked for, do ask for why it has been requested, since each has a variety of reasons].
• Speech Intelligibility tests and tests for Central Auditory Processing Disorders.

 

**Of these the most common is the first 3.

 

***ABR is mainly used to estimate hearing for young children and is difficult to test individuals.

 

Tests for hearing acuity/loss in children/paediatric population:

Young children or difficult-to-test individuals may not be able to respond in the manner required for audiometry and may thus give responses that are not reliable. However, with alternate tests, children as young as 2 days old can be assessed for hearing acuity. There are a number of tests that can be carried out;

1. OAE; Otoacoustic Emissions– this is a screening test that most hospitals carry out once the baby is born. It isn’t 100% reliable but is a good indicator of some hearing problems if done 3 times over a course of 2-4 months of age.

 

2. ABR; Auditory Brainstem Response- Very reliable and gives a good estimation of hearing levels. However, it takes about an hour to complete, sometimes lesser, sometimes more, depending on the child’s sleep and movements (the child has to be asleep and movements are normal even for a sleeping child) causing some more time to be taken for testing.

 

3. Behavioural Response Audiometry- Not very reliable, child’s responses (head and eye movements, vocalization) is seen to tones and voice. Children, very young ones especially wouldn’t respond to soft sounds. It thus becomes difficult to get an accurate estimate of hearing thresholds.

 

4. Visual Reinforced Audiometry- This is also a form of behaviour observation. But gives slightly better results than the test above, since the child may respond to even a soft sound (this is because an attractive screen/toy lights up every time tones/phonated vowels/words are presented).

 

5. Play Audiometry- This is like traditional audiometry but done with toys and is reliable when combined with careful observation of the child.

 

Once the required tests are carried out, further lines of action are decided depending on the degree and type of hearing loss.

Risk factors for hearing loss:

• Fluid in the middle ear (very specifically the repeated kind).
• Working or living in noisy situations for more than 8 hrs a day.
• Serious infections (meningitis, encephalitis, mastoiditis, mumps, tuberculosis).
• History of use of ototoxic drugs (quinone, tuberculosis medication, gentamycin etc.)
• Listening to very loud music, especially through headphones/earphones.
• Sudden noise/non-auditory trauma (blasts, slap to the face, serious injury to the face or skull).
• Any serious infection to the mother during pregnancy can cause hearing loss in the child (Toxoplasmosis, Maternal Rubella, Syphilis, Herpes Zoster etc.)
• Children with craniofacial abnormalities (Downs Syndrome, Pierre Robin Syndrome etc.)
• Frequent upper respiratory tract infections.
• Unchecked diabetes, hypertension.
• Family history of hearing loss.

 

I have been diagnosed with otosclerosis/ossicular chain fixation, what should I do?

This is a condition that causes the bone(s) of the ossicular chain to lose some/considerable movement. This happens because of the bone(s) get stuck and thereby become rigid due to various hormonal, and metabolic changes. This doesn’t happen to everyone and is very frequently hereditary.

Hearing loss isn’t apparent immediately but develops gradually due to overgrowth of the bone.

Depending on your age and the results of other tests, the doctor and audiologist decide on the best option. You could do well with just surgery, or may require getting surgery and wearing an aid. You also may just be asked to wear a hearing aid if age and recurrence are a factors.

I have middle ear fluid/middle ear pathology/otitis media, what are my options?

Filling of the area behind your eardrum with fluid is otitis media. It can be very painful, definitely will cause some conductive hearing loss and can be dangerous if infected.

It is easily detected during an otoscopic examination.

The doctor will first recommend management of the fluid either through medication and/or draining of the fluid.

If a greater than mild hearing loss persists due to on and off/chronic version of this condition, then a hearing device is recommended, with regular follow up.

What do I do if I have a ruptured eardrum/tympanic membrane?

This is best managed by an ENT. You may require a tympanoplasty (reconstruction of the eardrum using a skin graft), whereas small ruptures may heal spontaneously. Depending on your hearing levels after adequate medical intervention, a hearing device may or may not be prescribed.

Note that surgeries may not bring back complete hearing but are a very necessary step especially if you have an infection in the middle ear. Draining of the fluid and management of infection is primary.

I live/work in a place with high noise levels, what precautions do I take?

• Wear Hearing Protection Devices (HPDs).
• Regularly come (at least once in 4-6 months) for a hearing evaluation.
• If you suspect you already have developed a hearing loss/have tinnitus (ringing ears) then taking immediate action is necessary (getting assessed, changing the type of HPD you use).

My child has been diagnosed with hearing loss.

Children with conductive hearing losses are given medical intervention and follow up testing of hearing levels are recommended every 6 months (especially if the condition tends to be recurring).

Children with sensorineural hearing losses must use an assistive listening device depending on the extent of hearing loss. In the case of severe to profound degrees of hearing loss options are hearing aids/cochlear implants.

Even mild sloping hearing losses can cause persistent articulation/pronunciation errors. You might also observe some behavioural issues (especially in the classroom). Your child also may have difficulty understanding tonal changes in the voice.

It is best not to take hearing loss, even mild degrees, lightly. It has an impact in speech, language and academic development.

Some children with fluctuating middle ear pathology have been found to have CAPD (auditory processing issues) developing later on. This happens because of the varying auditory signals going to the brain. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3714994/

How is my child affected by hearing loss?

• Asking people to speak up since the listener is unable to hear them.
• Word confusions (some words in the conversation are mistaken for others).
• Music isn’t enjoyable.
• Increased difficulty understanding speech in fair to poor listening conditions (theatres, parties, noisy roads, rooms with a lot of echo etc.)
• Own voice may be too loud or too soft.
• Own speech is unclear (some sounds may be distorted, especially seen in children and adults with long-standing hearing loss).
• Behavioural issues in children (don’t pay attention, hyperactive).
• Classroom behaviour problems, academic difficulties.

 

What are my child’s options?

 

Medical intervention- Any or a combination of the following are done depending on a series of tests and their results (Audiometry, Tympanometry, Reflexometry, Otoscopy, Hearing aid trial, MRI etc.)

1. Wax removal.
2. Middle ear fluid management.
3. Management of ossicular chain fixation or discontinuity through insertion of a prosthesis (if recommended).
4. Cochlear implant.
5. Auditory brainstem implant.

 

Audiological intervention– Based on test results

1. Use of hearing aids.
2. Suggesting a Cochlear implant.
3. Use of non-verbal communication (sign-language and special schools/vocational training for the individuals with profound hearing loss or with auditory days-synchrony [no improvement with any assistive hearing device].

Auditory deprivation as Dr Mark Welch (ENT) would it is, “When the hearing nerves and the areas of the brain responsible for hearing are deprived of sound, they atrophy, or weaken.”

In older individuals (geriatric population) hearing aids can help with better communication and reduce frustration. Please feel free to click on the links given for evidence-based intervention benefits. 

Children in particular need hearing intervention at the earliest. 

 

I have/my child has hearing loss in just one ear/unilateral hearing loss:

There could be 2 scenarios to this:

1. One ear is normal and the other has a hearing loss

Fitting the affected ear with a hearing aid is necessary (provided the ear with hearing loss has up to a severe degree of hearing loss) because localizing sounds is difficult; incoming auditory stimuli is filtered better at the brainstem when there is comparable hearing in both ears. With children, even a mild unilateral hearing loss can disrupt classroom attentiveness and functioning.

 

2. One ear has better hearing than the other

This might lead to choosing to aid the poorer ear since the individual feels he/she/the child hears well enough through the better ear. Advice in this situation would be to aid both ears provided both have hearing losses of severe or a lesser degree- Binaural fitting. If the poorer ear has profound hearing loss then after careful consideration and trial, the poorer ear may also be aided.

What is important to remember is auditory deprivation. Any ear with loss in acuity that is left unaided will start to show signs of this. Fitting at a later time may not give the same results as fitting earlier since deprivation has progressed. The main effect of this is knowledge of the presence of an auditory signal, but confusion about what it is. Since the auditory pathway/cortex for that ear has in some way ‘atrophied’. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4134895/

What comes after fitting my child with a hearing aid?

Once fitted with a hearing aid/device, children will need therapy to develop speech and language skills.

This is because hearing through a device is different from natural hearing. Children with hearing impairment may miss subtle speech and language cues even with a hearing aid. Thus pronunciations are the most obviously affected. The next is syntax (grammar) and morphology (structure of a word in a particular context).

Children who wear an assistive listening device might also still have behavioural issues, which could be stemming from both missing linguistic cues and the psychological impact of having to wear a hearing aid/device.

Your child may, along with speech and language therapy/Auditory Verbal Therapy (AVT), also need counselling.

Please note that speech-language therapy and AVT are different from each other and the choice of which to take is best made by your hearing care provider depending on your child’s hearing loss, the onset of hearing loss and linguistic skills.