Hearing Loss: Causes, Symptoms & Next Steps

What is hearing loss?

Hearing loss is any reduction in the ability to detect sound compared to typical hearing. Sound travels a three-stage path from the outer ear, which funnels air pressure waves down the ear canal to the eardrum. Three small bones in the middle ear then amplify the sound to the cochlea in the inner ear, which converts the sound into nerve signals that the brain then interprets as speech. Damage along any point of this pathway causes hearing loss. The World Health Organization estimates more than 1.5 billion people live with some degree of hearing loss worldwide.¹

Hearing loss is not typically uniform across pitches. Most age-related hearing loss affects the high frequencies first, where people have a harder time differentiating between consonant sounds. This is why many people describe speech as being mumbled. The brain also adapts to a gradual loss, where the person with hearing loss is typically the last to notice, and family members usually raise their concerns first.

What are the three types of hearing loss?

The type of hearing loss that you have will determine the treatment options. For a more comprehensive look at the types of hearing loss, see our guide to types of hearing loss.

Conductive: sound has a harder time getting through the auditory system

This is caused by something either physically blocking or stiffening the path between the outside of the ear canal and the inner ear. This results in sound arriving attenuated, but the cochlea itself is healthy.

Common causes: Impacted earwax, middle-ear fluid or infection (otitis media), a perforated eardrum, otosclerosis, or a blocked Eustachian tube.
Outlook: A conductive type of hearing loss is typically reversible. Wax removal, treatment of an infection, or surgery for otosclerosis can all potentially restore hearing. A medical assessment is needed prior to the discussion of hearing aids.

Sensorineural: the signal is degraded

The hair cells of the cochlea, or the nerve carrying their signal, are damaged. This is the most common permanent hearing loss in adults, and it affects clarity as well as volume: making speech louder does not fully restore intelligibility, because the detail is lost before the brain receives it. Hair cells do not regenerate, so the loss is managed rather than cured.

Common causes: Ageing (presbycusis), cumulative noise exposure, some medications that are toxic to the ear, genetic factors, and sudden idiopathic loss.
Outlook: Permanent, but very treatable with hearing aids or — for severe to profound loss where aids no longer help — a cochlear implant assessment.

Mixed: both at once

A conductive problem layered on top of an existing sensorineural loss — for example, age-related inner-ear loss in someone who also has chronic middle-ear fluid. Testing separates the two components by comparing air-conduction and bone-conduction thresholds, and the conductive part is treated on its own merits before the remaining permanent loss is fitted.

Common causes: Any combination of the causes above, most often long-standing ear disease alongside age-related or noise-related loss.
Outlook: Partly correctable. Expect a two-part plan: medical treatment for the conductive element, amplification for what remains.

How is hearing loss measured?

A hearing test produces an audiogram: the quietest sound, in decibels hearing level (dB HL), that you can reliably detect at each pitch. Your threshold is then described in bands from mild to profound. The number is not a percentage of hearing “lost” — it is the volume a sound has to reach before you notice it, so a 50 dB HL threshold means everything quieter than 50 dB is effectively inaudible to you. The tool below moves a threshold across those bands and shows which everyday sounds fall above and below it.²

Threshold explorer

Drag to move the hearing threshold

40dB HL

Mild hearing loss

Quiet speech and consonants get lost. One-to-one conversation in a quiet room is usually fine; group conversation and background noise are not.

20 dBRustling leavesInaudible
30 dBA whisperInaudible
40 dBQuiet libraryOnly just audible
50 dBRefrigerator humOnly just audible
60 dBNormal conversationClearly audible
70 dBVacuum cleanerClearly audible
80 dBCity trafficClearly audible
95 dBMotorcycleClearly audible
110 dBChainsawClearly audible

Simplified for explanation: a real audiogram plots a separate threshold for each frequency, and audibility also depends on the pitch of a sound, not just its loudness.

What are the early signs of hearing loss?

Hearing loss typically happens gradually over many years. Tick anything below that sounds like something you have recently experienced.

Signs checklist

Not a diagnosis — a prompt to book a test

You ask people to repeat themselves, or answer with “pardon?” several times a day.
Conversation in a restaurant, car or busy room is far harder than one-to-one in a quiet room.
Others say the television or radio is too loud at the volume you find comfortable.
Speech sounds mumbled rather than quiet, and women’s and children’s voices are hardest to follow.
You miss the doorbell, the microwave, a reversing alert or a phone ringing in another room.
You watch faces and lips closely to keep up, and telephone calls are noticeably harder than in person.
You have ringing, buzzing or hissing in one or both ears.
You avoid gatherings, meetings or family events because following them is tiring.

Nothing ticked yet

Work through the list above. Recognising two or three of these is the point at which most people benefit from a baseline test — including a result that turns out to be normal, which gives you something to compare against later.

This checklist is a prompt to book a test, not a diagnosis or a hearing screening. Only a hearing assessment can measure your thresholds.

What causes hearing loss?

Most adult hearing loss in Canada comes down to two causes acting together over years. Age-related hearing loss (presbycusis) is a gradual, symmetrical, high-frequency sensorineural hearing loss reflecting cumulative wear on cochlear hair cells. Noise-induced hearing loss is caused by exposure to sound intense enough to damage the hair cells, whether in one blast or across years of exposure. Risk rises with prolonged exposure above roughly 85 dB(A), and it is the one major cause that is almost entirely preventable.¹

Ageing (presbycusis) — gradual and usually symmetrical, taking high frequencies first.
Noise exposure — occupational (trades, agriculture, manufacturing, music) or recreational (firearms, power tools, personal audio at volume).
Earwax and obstruction — a common, entirely reversible conductive cause, and the first thing worth ruling out.
Middle-ear infection or fluid — the most frequent cause in children, and a recurring conductive cause in adults.
Ototoxic medication — certain antibiotics, chemotherapy agents and high-dose salicylates can damage the inner ear; never stop a prescribed drug on your own, but do raise hearing changes with the prescriber.
Otosclerosis and other structural conditions — abnormal bone growth stiffening the middle ear, often surgically treatable.
Genetics and family history — influences both congenital loss and susceptibility to age-related loss.
Head injury, barotrauma or sudden idiopathic loss — abrupt onset, and a reason to seek care immediately rather than wait.

See someone urgently, not eventually

Most hearing loss can wait for a routine appointment. These cannot — treatment for sudden sensorineural hearing loss is most effective when started within 72 hours:

Hearing that drops suddenly, especially in one ear only
Hearing loss with pain, discharge or bleeding from the ear
Hearing loss with dizziness, vertigo or facial weakness
Sudden ringing in one ear alongside a change in hearing
Any hearing loss following a head injury

If you experience any of the above symptoms, call a hearing care professional immediately or go to a walk-in clinic or emergency department.

What happens when you get your hearing checked?

A hearing assessment is painless and typically takes under an hour to complete. A hearing care professional will start with a case history and take a look inside the ear canal with an otoscope. Testing then establishes your thresholds pitch by pitch through headphones, adds a bone-conduction comparison to separate conductive from sensorineural hearing loss, and usually includes a speech-in-noise measure. This test produces an audiogram, which gives the hearing care professional a bigger picture of your current hearing. Our guide to what to expect at a hearing test walks through the appointment and your audiogram in more detail.

Common questions

Can hearing loss be reversed?

Conductive hearing loss can often be reversed by removing impacted wax, clearing middle-ear fluid caused by an infection, or operating on otosclerosis, which may restore hearing to previous levels. Sensorineural hearing loss cannot be reversed, because the cochlear hair cells involved do not regenerate. It is, however, highly treatable. Hearing aids restore access to the sounds you are missing, and cochlear implants can be prescribed when loss is severe to profound and hearing aids no longer deliver useful speech understanding.

Is hearing loss in one ear a problem if the other is fine?

Yes, and it warrants prompt assessment. Two working ears are what let the brain locate sound and separate a voice from background noise, so single-sided loss is disproportionately disabling in groups and traffic. A new one-sided loss also needs a medical cause ruled out, since asymmetry can point to something specific rather than general wear — and if it came on suddenly, treat it as urgent.

Does untreated hearing loss affect anything beyond hearing?

Research has associated untreated hearing loss with social withdrawal, listening fatigue and accelerated cognitive decline. The strength of this link and the extent to which treatment changes the trajectory are still being studied, so it is fair to say the association is well established although not fully understood.

How often should adults have their hearing tested?

There is no single mandated interval for Canadian adults. A practical approach is a baseline test once in your fifties, then every two to three years, and annually if you are over 60, work in noise, have tinnitus, or have noticed a change. Anyone with a known loss should retest annually so that hearing aid settings keep pace with their thresholds.

Do I need a doctor’s referral to get a hearing test?

To have your hearing tested at a private health clinic there is no need to have a doctor’s referral, although each province has its own requirements for assessment and provincial funding eligibility. It is best to consult with your family physician first to see their recommendations.

Sources

World Health Organization — Deafness and hearing loss fact sheet. Global prevalence and noise-exposure risk thresholds.
Degree of hearing loss classification in common clinical use — mild 26–40, moderate 41–55, moderately severe 56–70, severe 71–90, profound 91+ dB HL. After Clark, J. G. (1981), Uses and abuses of hearing loss classification, as published by the American Speech-Language-Hearing Association. Statistics Canada uses ASHA definitions for hearing loss in its Canadian Health Measures Survey reporting.

This guide is general information about hearing health, not medical advice, and it cannot substitute for an assessment by a qualified hearing professional. If you are concerned about your hearing, book an appointment with an audiologist, hearing instrument practitioner or your physician.

Hearing loss: causes, symptoms and next steps