Hearing loss is the partial or total inability to hear sound from one or both ears. The condition has grown increasingly common in recent years due to population aging, increased noise exposure, and unsafe listening habits. Loud sounds can cause inner ear hair cells to bend and eventually die over time. More than 5% of the world's population, or some 430 million people, have disabling hearing loss.
For many people with hearing loss, hearing aids can amplify sound and help improve quality of life. These electronic devices can also stave off other injuries since untreated hearing loss amplifies the risk of dementia, cognitive decline, and falls.
Deaf people, meaning those with little or no hearing, may use one of the more than 300 global sign languages to communicate. Cochlear implants are another option, and they have become increasingly affordable. They help deaf people experience the sensation of sound by converting it into electrical impulses that are sent on to the auditory nerve (bypassing inner ear cells entirely). The auditory nerve then transmits those impulses to the brain. The implant uptake has sparked controversy about maintaining aspects of deaf culture and promoting sign language education.
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This video walks through the biology of why presbycusis (prez-buh-kyoo-sis) occurs and its etiology. This type of hearing loss is gradual and typically starts with reductions in the ability to hear high-pitched sounds.
Disabling hearing loss is defined as hearing loss greater than 35 decibels in the better hearing ear. (For context, that means the sound of leaves rustling, at roughly 30 decibels, would be inaudible even to your better-hearing ear.) The World Health Organization's data suggests that more than 5% of the world's population has this level of loss requiring rehabilitation, which amounts to 430 million people—including 34 million children.
From the sound of a ticking watch, which is roughly 20 decibels, to the sound of a gunshot at 140 decibels, the Hearing Health Foundation breaks down the decibels of daily sounds in this chart, noting that sounds louder than 70 decibels are considered harmful.
Gene therapy for profound genetic deafness has been advancing in recent years, with multiple clinical trials enabling hearing at normal levels for the first time without hearing aids or cochlear implants. The therapies target hearing loss caused by mutations in the OTOF gene that codes for a protein called otoferlin. That protein normally plays a key role in relaying sound signals in synaptic transmission between the ear's inner hair cells and the auditory nerve.
This science teacher video systematically walks through the biology of the outer, middle, and inner ear. The explanation starts with the auricle, an external part that funnels sound through the auditory canal, and the tympanic membrane (the ear drum), which vibrates when sounds hit it. Beyond that, as the video details, is the eustachian tube, which is connected to the back of our throats and allows air to pass in and out to equalize ear pressure.
This 2023 data from the Institute for Health Metrics and Evaluation shows the estimated number of people with complete hearing loss in different age groups per 100,000 people in the population. Individuals aged 70 or older make up the largest group with this type of hearing deficit.
This conclusion comes from research published in 2025 that analyzed self-reported hearing loss and hearing aid use from long-term studies that covered 28 countries. Its findings included that the countries with the greatest prevalence of hearing loss (China, South Korea, Mexico, and Brazil) also had the lowest levels of hearing aid use.
The devices, available in recent years, are typically more affordable than prescription ones and are intended for people with mild to moderate hearing loss, yet surveys suggest people often don't feel comfortable choosing one on their own. The nonprofit Consumer Reports ranked available OTC options to help patients navigate the market.
The three-person boy band—whose members have different levels of hearing loss—use light systems, vibrations, and a mix of Korean and American Sign Languages, as well as International Sign (which isn't a whole language), to communicate and keep their dance routines in sync. In this interview, a band member with partial hearing describes their challenges.
The Museum of Deaf History, Arts and Culture—a small, independent museum—documents discrimination against the deaf and the unique culture and history of people with hearing loss in the US.
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