Deafness & Hearing Loss: Types, Symptoms, Causes, Treatment

When individuals lose their average hearing ability, they are said to have hearing loss. Many causes and factors can affect the hearing of an individual. Hearing loss can occur at any age. But most commonly, it is experienced in old age. 

Approximately 1 billion young people risk developing permanent but avoidable hearing loss. There is an estimate that about 2.5 billion people will have some hearing loss level by 2050. At least 700 million people will need rehabilitation for hearing by 2050. 

The human ear is divided into the outer ear, middle ear, and internal ear. The sound enters the ear and strikes the tympanic membrane. It vibrates the tympanic membrane. These vibrations reach the ossicles, thereby vibrating them. These vibrations then reach the cochlea, the part of the inner ear. It results in the stimulation of the basilar membrane and organ of Corti. These vibrations are finally transformed into impulses and reach the brain.

According to the definitions of hearing loss, the British Society of Audiology categorized the severity of hearing loss based on the decibel hearing level range. These ranges are:

1. Mild hearing loss (21–40 dB)
2. Moderate hearing loss (41–70 dB)
3. Severe hearing loss (71–95 dB)
4. Profound hearing loss (95 dB or above)

People with profound hearing loss are considered as deaf. 

When individuals lose their average hearing ability, they are said to have hearing loss. Many causes and factors can affect the hearing of an individual. Hearing loss can occur at any age. But most commonly, it is experienced in old age. More than 25% of people are affected by hearing-loss problems when they reach above sixty years of age. Although there may not be a definite cure for hearing loss, it can always be treated by determining the causes, symptoms, and severity. 

Based on the level of hearing problems, patients can be divided into the following three types:

1. Patients with hearing loss: Patients who are unable to hear, similar to people with normal hearing, i.e., 20 dB or better in both ears- have hearing loss. The patients may have mild, moderate, or severe hearing loss. The hearing ability is affected in one or both ears. These patients have difficulty having a conversation with other people.
2. Patients hard of hearing: People who cannot hear a sound of 21 to 94 dB or above are categorised as hard of hearing. Such people have mild to severe hearing loss. They usually communicate with other people through spoken language. These patients are benefitted from cochlear implants, hearing aids, and other devices. 
3. Deaf people: People with profound hearing loss are said to suffer from deafness. It indicates very little or almost no hearing. Such people use sign language for everyday communication. People who cannot hear a sound of 95 dB or above are called deaf (profound hearing loss).

Hearing loss and Deafness can be caused due to the effect of different steps of the hearing process. Deafness can be of the following types:

1. Conductive: In this condition, the sound cannot enter the outer or middle ear. Even if there is any hearing, the patient cannot hear the soft sound. It may be due to the malformation of the outer or middle ear or the presence of infection. 
2. Sensorineural: Patients with sensorineural deafness have a problem in their inner ear, or their auditory nerve is affected. Such patients have permanent hearing loss. The causes of sensorineural hearing loss are inner ear malformation, trauma, or toxic effects of drugs. 
3. Mixed: These patients have both conductive as well as sensorineural hearing loss. 
4. Unilateral and bilateral deafness: Unilateral hearing loss indicates profound hearing loss in one ear, while a bilateral hearing loss means profound loss of hearing in both ears. 
5. Prelingual and postlingual deafness: Prelingual deafness indicates profound hearing loss before a child develops language and speech. In postlingual deafness, profound hearing loss occurs after a child develops language and speech.
6. Age-related hearing loss: The patients may also have hearing loss due to ageing. As the person gets older, there is an alteration in the auditory nerve and inner ear that reduces the ability to hear. 

Patients with deafness have the following symptoms:

1. Muffling of the sound or speech
2. Requesting people to speak slowly or loudly
3. Need to raise the volume of phones, radios, television, or other audible devices
4. Unable to understand words or speech, especially in crowded surroundings
5. Difficulty in hearing words clearly
6. Telling the other person to repeat very often
7. Turning the volume up (of radio, television, etc.)
8. Unable to talk to people in noisy settings (parties, group meetings, in a crowd)
9. Difficulty in understanding even after hearing
10. Withdrawal from social gatherings and conversations
11. Trouble hearing consonants
12. Ringing in the ears or tinnitus

These symptoms make these patients avoid taking part in conversations. It results in loneliness and isolation. It is also essential to consider that signs of deafness in adults are different from children. The child is screened for hearing issues either at the time of birth or within one month. Some symptoms of child deafness are speech delay, not following what is being told, and raising the volume of audible devices. 

1. Loud Noises: Exposure to high decibels of noise can damage the inner ear. Due to loud noises, the nerve cells on the cochlea may tear down. The cochlea is a hollow, spiral-shaped cavity in the inner ear with nerve cells that receive sound signals and send them to the brain. When these nerve cells are damaged, the electrical signals are not transmitted, affecting the hearing ability. Loud noises can also rupture the eardrum. 
2. Ageing: It is the most common cause of hearing loss. With age, the nerve cells start deteriorating gradually, causing damage to the inner ear. This condition is most commonly known as presbycusis. In most old-aged people, hearing is affected in both ears, and high-pitched sounds are the hardest to hear. 
3. The Buildup of Earwax: When too much earwax is built up in the inner ear, it starts blocking the ear canal. Due to the blockage, the conduction of sound waves gets difficult. 
4. Illnesses: Many illnesses and autoimmune diseases can lead to hearing loss. For example, the immune response in Meniere's disease affects the outer and middle ear. Sometimes an abnormal growth of an ear bone can also cause hearing loss.

Causes of conductive deafness

1. Accumulation of fluid in the ear
2. Outer or middle ear malformations
3. Presence of ear wax or foreign objects in the ear
4. Eardrum with hole
5. Ear infection (in the middle ear)

Causes of sensorineural deafness

1. Underlying medical conditions such as otosclerosis, acoustic neuroma, Meniere's disease, viral infections, and autoimmune diseases like Cogan's syndrome
2. Exposure to the deafening sound
3. Head trauma
4. Toxic effects of drugs such as antibiotics and cancer drugs
5. Premature delivery, low birth weight, and inner ear malformation
6. Intrauterine infections and birth asphyxia (in babies)

How to Prepare for the Doctor's Consultation? 

Before visiting a doctor, consider the following points: 

1. Make a prior appointment with the doctor. 
2. Develop a communication plan with everyone who may be seen in the hospital, including the receptionist, nurse, doctor, and lab technician. 
3. Keep a record of the medical history and all the medications on the day of the visit. 
4. Make a list of questions that need to be asked the doctor. 
5. Bring an interpreter or family member to communicate with the hospital staff. 

      The doctor may ask the following questions:

1. When did the patient start experiencing the symptoms? 
2. Is there any previous record of infections in the ear? 
3. Has anyone from the patient's family suffered from hearing loss before? 
4. Is there any record of a head injury? 
5. What questions can be asked of the doctor? 
6. What kind of communication services are provided in the hospital? 
7. Can an interpreter or someone from the family stay during the examination and treatment? 
8. What diagnostic tests does the patient need? 
9. What are the risks and benefits involved in using hearing aids? 

Age-Related

1. Inherited hearing loss 
2. Otosclerosis - affecting the movement of the tiny bones in the middle ear
3. Sensory neural degeneration

Generic

1. Middle ear infections 
2. Continuous exposure to loud noises (recreational or occupational)
3. Heart disease or diabetes
4. Consumption of medicines such as aspirin, antibiotics (such as Streptomycin and Neomycin)
5. Head injury
6. Smoking

Taking the necessary precautions can help in preventing hearing loss. Mentioned below are the ways to avoid noise-induced and age-related hearing loss: 

1. Avoid Listening to Loud Music: Exposure to loud noises and music for long hours can adversely affect hearing. Reduce the hours of listening to music and while listening to music, stay mindful about not playing the music too loud. Take necessary precautions while going for recreational activities like hunting, listening to rock concerts, riding a snowmobile, etc. 
2. Shield Your Ear: If an individual's working environment is too loud, then wearing plastic earplugs or glycerin-filled ear muffs helps to protect the ears. Contaminated water in the swimming pool can also cause infection in the ear, so protecting the ears while swimming is also necessary. 
3. Rational Use of Medicines: Check the side effects of medicines before consumption to avoid ototoxicity. Ototoxicity is the damage caused to the ears due to taking certain medications. It can lead to hearing loss, ringing in the ears, or balance disorders. 
4. Early diagnosis and management of common ear conditions.
5. Genetic counselling
6. Good practices for child and maternal health.

It is important to diagnose and treat ear conditions at an earlier stage. There should be a systematic screening of patients for hearing loss who are at increased risk. These include preschool and school-age children, infants, the elderly, people working in environments with chemical and sound exposure, and patients taking ototoxic drugs. There should be routine ear examinations in community settings. WHO “hearWHO” app and other technology-oriented tools are effective in screening people for hearing loss.  The doctor diagnoses deafness through the following methods:

1. Otoscopic examination: The doctor performs a comprehensive otoscopic examination to determine the cause of hearing loss. 
2. Audiometric tests: During these tests, the doctor directs the sound through the headphones into each ear at varying loudness. It helps in determining the quietest sound the patient can hear. 
3. Whisper test: The doctor whispers in the ear of the patient to determine the hearing level of the patient. 
4. Tuning fork test: Tuning fork tests are used to differentiate between sensorineural or conductive hearing loss. In the Weber tuning fork test, the vibrating fork is placed at the midline forehead. If the sound is equal in both ears, hearing is normal. However, if the sound lateralizes in one ear, there may be a hearing problem. 
5. Behavioural assessment techniques: The doctor performs certain behavioural assessment tests on children to determine how well they are hearing and responding to the instructions. 
6. Routine screening of children: There should be routine screening in infants, babies, preschool and school-going children to identify and treat ear disease and hearing loss at an early stage. 

Treatment of deafness and Hearing loss aims either to remove the cause or to improve the hearing ability of the patients through external devices. Once the cilia and auditory nerves are damaged, they cannot be repaired. Some of the treatment options include:

1. Removal of blockage: Removal of the blockage, such as wax impaction, overgrowth, or foreign objects, may restore hearing.
2. Hearing aids: Hearing aids, such as behind-the-ear aids, in-the-ear aids and in-the-canal aids, and cochlear implant help to improve hearing. However, the cochlear devices stimulated the auditory nerve. Thus, if the auditory nerve is damaged, these devices will not work.
3. Medications: Some of the medications help to restore hearing. These include antibiotics to treat infection and corticosteroids to reduce inflammation.  
4. Surgery: Surgery may help patients with hearing loss or deafness due to anatomical malformations. The surgeon corrects the problems in ear bones or ear drums through surgery. 

If hearing loss remains unaddressed, the affected individuals may face the following problems: 

1. Social Isolation: People who have hearing loss face problems with daily communication. Their interaction with loved ones also fades away due to their inability to hear. These changes in health and social connections can lead to isolation and loneliness.
2. Cognitive Impairments: If hearing loss remains unaddressed in children or young adults, it can affect their communication and even impact their memory. Children with hearing loss also face problems in their ability to study. 
3. Disease Progression: When the patient goes to an audiologist, he/she may describe the condition of hearing loss as mild or severe, depending on the test results. These descriptions signify the degree of hearing loss.