👂 Hearing Health: Causes of Decline, Prevention and Protection Against Hearing Loss

Hearing is one of the five basic senses; it allows us to communicate, enjoy music, react to danger and experience the richness of the world around us. According to the World Health Organization, more than 1.5 billion people on the planet have some degree of hearing loss, and by 2050 this number could rise to 2.5 billion. Hearing loss is the third most common chronic health condition in the world after arthritis and heart disease. Yet many forms of hearing loss can be prevented if action is taken in time.

How the ear works and how we hear

The human auditory system is a remarkably complex mechanism made up of three main parts.

The outer ear includes the auricle (pinna) and the ear canal. The auricle collects sound waves and directs them into the ear canal. The shape of the auricle is no accident: its curves help determine the direction of sound and amplify the frequencies that matter for understanding speech.

The middle ear is an air-filled cavity behind the eardrum that houses the three smallest bones in the human body: the malleus (hammer), the incus (anvil) and the stapes (stirrup). When a sound wave reaches the eardrum, it begins to vibrate, passing the vibrations along the chain of ossicles. The stapes, the smallest bone, weighing about 3 mg, amplifies the pressure roughly 20-fold and transmits the vibrations to the oval window of the inner ear.

The inner ear contains the cochlea, a spiral-shaped, fluid-filled tube. Inside the cochlea lies the organ of Corti, the receptor apparatus of hearing. Its hair cells (about 15,000 of them) convert the mechanical vibrations of the fluid into electrical nerve impulses. The outer hair cells amplify quiet sounds, while the inner ones generate the signal for the auditory nerve. From there, the impulses travel to the temporal lobes of the cerebral cortex, where we actually "hear" and interpret sound.

Types of hearing loss

Depending on which part of the auditory system is damaged, there are three main types of hearing loss:

Conductive hearing loss is caused by impaired conduction of sound through the outer and middle ear. Causes include earwax plugs, foreign objects in the ear canal, a perforated eardrum, fluid in the middle ear (with otitis) and otosclerosis (abnormal growth of the stapes bone). This type of hearing loss is often reversible: once the cause is removed, hearing can be fully restored.

Sensorineural hearing loss occurs when the hair cells of the cochlea or the auditory nerve are damaged. It is the most common type of hearing loss. Causes include noise damage, age-related changes, genetic factors, infections (meningitis, measles), ototoxic medications and head injuries. Hair cells do not regenerate, so the loss is irreversible.

Mixed hearing loss is a combination of conductive and sensorineural components. For example, an older person with age-related hearing loss (the sensorineural component) may develop otosclerosis (the conductive component).

Noise-induced hearing loss

Noise trauma is one of the most frequent and entirely preventable causes of hearing loss. It develops with regular exposure to sounds above 85 decibels (dB) or after a single extremely loud sound (a gunshot or explosion, over 140 dB).

For reference: normal conversation is 60 dB, city traffic 70–85 dB, a motorcycle without a silencer 95 dB, a rock concert 110–120 dB, and an aircraft at take-off 130 dB. Every 3 dB increase doubles the intensity of the sound, and the safe exposure time is cut in half: 8 hours at 85 dB, 4 hours at 88 dB, 2 hours at 91 dB and 15 minutes at 100 dB.

Occupational noise-induced hearing loss develops in workers in noisy industries (construction, mining, aviation), as well as in musicians and DJs. Recreational hearing loss comes from loud music in headphones, concerts, shooting ranges and motorsports. Teenagers and young adults are especially vulnerable: the WHO warns that more than 1 billion young people aged 12–35 are at risk of losing their hearing due to excessive use of headphones.

The 60/60 rule: listen to music on headphones at no more than 60% of maximum volume and for no longer than 60 minutes at a time. Use noise-cancelling headphones: they let you listen at a lower volume without having to drown out the noise around you.

Age-related hearing loss (presbycusis)

Presbycusis is a gradual loss of hearing associated with the natural ageing of the auditory system. It begins as early as after age 30, but usually becomes noticeable after 60. By age 65, one in three people has significant hearing loss, and by 75, one in two.

High frequencies are affected first: a person stops being able to make out whispers, children's voices, a ringing phone or birdsong. Speech becomes less intelligible, especially in noisy settings such as a restaurant, a meeting or public transport. Many put this down to inattentiveness without suspecting hearing loss.

Age-related hearing loss is made worse by accompanying factors: lifetime noise exposure, vascular diseases (diabetes and hypertension impair blood supply to the cochlea), genetic predisposition, smoking and ototoxic medications.

Tinnitus (ringing in the ears)

Tinnitus is the perception of sound in the absence of an external source: ringing, humming, whistling, hissing or pulsing. It affects 10–15% of the adult population, and for 1–2% it becomes severe, interfering with normal life.

Tinnitus is not a disease in its own right but a symptom. The most common causes are noise damage, age-related hearing loss, earwax plugs, ototoxic medications (high-dose aspirin, some antibiotics, diuretics), Ménière's disease, otosclerosis and TMJ dysfunction (a disorder of the temporomandibular joint). Sometimes the cause cannot be identified.

Treatment of tinnitus depends on the cause. If the cause can be removed (an earwax plug, a medication), the noise may go away. In chronic cases, the options include sound therapy (masking the noise with white noise or special sounds), cognitive behavioural therapy (changing one's reaction to the noise), hearing aids (when hearing loss is also present, amplifying external sounds distracts the brain from the tinnitus) and neuromodulation. It is important to avoid silence (it intensifies the perception of the noise), manage stress and get sleep back to normal.

How hearing loss affects quality of life

Hearing loss is far more than an inconvenience in conversation. Research shows that untreated hearing loss has serious consequences:

• Social isolation. It becomes hard for a person to take part in conversations, and they start avoiding get-togethers, events and phone calls. This leads to loneliness and depression.
• Cognitive decline. A Johns Hopkins University study found that even mild hearing loss doubles the risk of dementia, moderate loss triples it, and severe loss increases it fivefold. The brain spends too many resources decoding sounds, leaving less for memory and thinking.
• Depression and anxiety. The risk of depression in people with untreated hearing loss is 50% higher. The constant strain of trying to hear the other person drains emotional resources.
• Reduced safety. A person may not hear an alarm, a car horn or a warning of danger.
• Problems at work. Communication difficulties reduce productivity and can lead to job loss.

Diagnosing hearing problems

Timely diagnosis is critically important: the earlier hearing loss is detected, the more effective the help. The main methods are:

Pure-tone audiometry is the "gold standard" of diagnosis. Wearing headphones, the patient presses a button whenever they hear a tone of a certain frequency and volume. The result is an audiogram showing the hearing threshold at each frequency.

Tympanometry assesses the mobility of the eardrum and the pressure in the middle ear. It helps detect fluid behind the eardrum, a disruption in the chain of ossicles or a perforation.

Otoacoustic emissions (OAE) testing records the sounds generated by healthy outer hair cells in the cochlea. The method is especially useful for hearing screening in newborns.

You should see an ear, nose and throat specialist (ENT doctor) at the first signs of hearing loss: frequently asking people to repeat themselves, needing to turn up the TV, having trouble following speech in a noisy room, ringing or noise in the ears, or a feeling of blocked ears.

Ototoxic medications

Some medications can damage the hair cells of the cochlea and cause irreversible hearing loss or tinnitus. Ototoxic drugs include:

• Aminoglycoside antibiotics (gentamicin, streptomycin, amikacin), especially when given intravenously.
• Loop diuretics (furosemide), usually at high doses.
• Salicylates (aspirin), when therapeutic doses are exceeded; the effect is usually reversible.
• Platinum-based drugs (cisplatin), used in chemotherapy for cancer.
• Antimalarial drugs (quinine, chloroquine).

When potentially ototoxic drugs are prescribed, hearing must be monitored: audiometry before treatment begins and regularly during it.

Ear care and prevention

Proper ear care is simple, but many people make mistakes:

• Do not use cotton buds to clean the ear canal. They compact the wax, pushing it deeper, and can damage the eardrum. Ears clean themselves: wax gradually migrates outwards and is removed when you wash the outer ear.
• If you have earwax plugs, see a doctor. They will remove the plug by irrigation or with special instruments. At home you can use wax-softening drops from the pharmacy.
• Protect your ears from noise. Wear earplugs or ear defenders in noisy workplaces, when shooting, at concerts and when using power tools.
• Dry your ears after swimming: moisture in the ear canal creates an environment for bacteria (otitis externa, "swimmer's ear").
• Treat infections promptly. Untreated chronic otitis media can damage the ossicles and lead to permanent hearing loss.
• Look after your general health: diabetes, hypertension and high cholesterol impair blood supply to the cochlea.

Hearing aids and rehabilitation

Modern hearing aids have come a long way from the bulky devices of the past. Digital hearing aids automatically adjust to the sound environment, suppress feedback (whistling), pick out speech from noise and connect to a smartphone via Bluetooth. Miniature models are practically invisible.

Research shows that wearing hearing aids for hearing loss slows cognitive decline, reduces the risk of depression and improves social connections and quality of life. The sooner you start using them, the faster and more easily the brain adapts to amplified sound.

In severe and profound hearing loss, when hearing aids are ineffective, a cochlear implant may be recommended: a device that stimulates the auditory nerve directly with electrical signals, bypassing the damaged hair cells.

Myths about hearing

There are quite a few misconceptions: "hearing loss is only a problem for older people" (noise-induced hearing loss is affecting younger people with every decade), "if I couldn't hear well, I'd know" (the loss builds up gradually, and the brain compensates for it for as long as it can), "a hearing aid is a sign of old age" (modern devices are no more noticeable than Bluetooth earbuds), "you can't lose your hearing from headphones" (music at maximum volume in in-ear headphones damages hearing just as much as industrial noise).

Take care of your hearing: avoid excessive noise, protect your ears in noisy conditions, have your hearing checked regularly after age 50 and don't put off seeing a doctor at the first signs of a problem. Hearing is your connection to the world, and it is worth preserving.