The decibel scale measures sound intensity, with hearing damage occurring after prolonged exposure to sounds above 85 decibels—equivalent to a noisy lawnmower.

See this graphic describing what different decibel levels mean for hearing loss.

More than 5% of the world's population has disabling hearing loss

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.

One decibel of hearing loss increases tinnitus risk by 6% for older people

That's according to an analysis of more than 18,000 people published in BMC Medicine in 2023. The tinnitus risk is not just limited to older people: The research also concluded that one decibel of hearing loss increases the risk of developing tinnitus among young adults by 3 percent.

Mapping hearing loss in the US

Nearly 10% of Americans suffer from some degree of hearing loss, measured as the inability to hear sounds lower than 25 decibels. The incidence of hearing loss increases with age and is typically higher among men. Recent analysis produced a puzzling observation researchers can't quite explain: There's a larger incidence of hearing loss among rural populations than in urban centers. Explore the data with this map and explainer.

Pickleballs' loud 'pop' sound can reach 120 decibels, equivalent to the sound of a hammer striking a nail.

'Silent' fireworks are not entirely noise-free

By using a reduced amount of flash powder—the ingredient responsible for the loud explosions that fireworks make—"silent" fireworks produce displays between 70 and 90 decibels, rather than the approximately 175 decibels heard in professional displays.

See what loud noises do to inner ear hair cells

This animation illustrates how louder music can affect inner ear hair cells. Damage to these cells is generally considered permanent. Hearing protection like ear plugs can reduce the level of sound entering into the ear and help protect those cells.

Hearing loss can affect balance and make falls more likely

For reasons that are not yet fully understood, hearing loss seems to increase the risk of falls. One explanation is that reduced environmental awareness due to hearing loss may put people at greater risk. Another theory is that the brain has to work harder to process sound with hearing loss and that cognitive load may also boost the chances of falls. One study found that for every 10 decibel increase in hearing loss, there was a 1.4 fold increased odds of falling in the preceding 12 months.

See worldwide hearing loss by age group and country

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.

Objects that move faster than the speed of sound—Mach 1—create shockwaves called sonic booms by building up and forcing sound waves to combine as they lag behind the object.

If hearing is damaged, the brain may amplify remaining sounds, perhaps causing tinnitus

Recent mouse brain and ear imaging revealed that the creature compensates for hearing loss by sending signals to the cochlea in the inner ear. This triggers nerve fibers in the inner ear to increase volume and become more sensitive. Learning about these boosted-sensitivity messages from the brain to the cochlea—if they're similar in humans—might help explain tinnitus and fuel experimental approaches to turn down that sensitivity.

Try out an online tone generator, which produces sounds of specific frequencies to help tune instruments, test your hearing, and generate beats by overlapping tones.

Watch how your nervous system's efforts to process silence can contribute to tinnitus

Cochlear cells can be damaged in numerous ways, including aging or exposure to loud noise. If enough cells die, the auditory system can become less sensitive, prompting the brain to compensate by amplifying sound, which is likely to contribute to tinnitus.

A magnitude 25 earthquake would release enough energy to destroy the sun, while a particle of dust drifting onto a table would have a magnitude of about -15.

The bullwhip was the first human-made object to break the sound barrier, producing a small sonic boom heard as a crack when flicked quickly.

People with tinnitus should avoid silence—sound-rich environments distract the brain

This podcast from an audiologist discusses common questions about tinnitus. It notes that tinnitus could be described as a phantom sound associated with hyperactivity in the brain. It's linked with loud sound exposures above 85 decibels, hearing loss associated with aging and stress, among other factors.

The Grateful Dead pioneered a massive 3-story, 75-ton, 600-speaker sound system that revolutionized live audio in the early 1970s.

Tinnitus estimates vary, but may occur in 10%-15% of the population

This video discusses the mechanisms underlying tinnitus and explores the knowns and unknowns about the condition. Tinnitus most commonly occurs among those with hearing loss, suggesting that cochlear damage may be a factor.

Hearing loss is linked with brain volume reductions

The brain looks different as a result of hearing loss, with reductions in brain volume overall and in specific areas, and these changes are hypothesized to impact cognition. Exactly why hearing loss alters cognition is an active area of research, but theories include that the elevated cognitive load of straining to hear affects brain power available for thinking and memory and that hearing loss leads to social isolation which boosts dementia risk.

In television and film, certain sounds, such as dialogue, may be difficult to understand due to sound mixing, device limitations, and technological advancements that have collectively reduced clarity.

Thunder occurs when fast-flowing electricity heats and pressurizes air, causing it to expand and produce a shockwave at each point along the bolt at multiple frequencies.

Within an anechoic chamber, all surfaces are covered with specialized materials that prevent wave reflection, helping prevent sound from echoing in the space.

When common sounds become disturbing

Misophonia causes certain sounds to feel violating, triggering a "very visceral kind of experience" filled with extremely unpleasant emotions, including annoyance, anger, and disgust. A 2017 study found that people with misophonia have elevated activity in the brain's anterior insula—a region associated with interoception, emotional processing, and behavioral responses—when exposed to trigger sounds. Ongoing research suggests trigger sound context affects the severity and manifestation of the condition.

Stonehenge may have functioned as an echo chamber designed to keep ceremonies secret from outsiders.

Acoustics researcher Trevor Cox discovered that Stonehenge acts like a concert hall, reflecting and amplifying sound. This video shows Cox demonstrating the effect using a scale model inside a soundproof studio.

How 'vibes' factor into scientists' decisions about using certain units

Although there are absolute quantities from which units can be defined, such as the speed of light and the corresponding light year for distance, the usefulness of units comes from their ability to easily communicate values, rather than how fundamental their origins are. For example, while Kelvin measures absolute temperature, Celsius is scaled to the temperatures of boiling and freezing water, making them more practical for everyday usage.

The three smallest bones in the human body—the malleus, incus, and stapes—amplify the vibrations of sound waves by almost 20 times to help enable hearing.

A sound's pitch will seem to change if the listener or the source moves toward or away from the other because motion changes the time it takes each successive sound wave to reach the listener.

Visualize the power and frequency of earthquake magnitudes.

What Stonehenge sounded like

Researchers built the first scale model of the world's best-known prehistoric stone circle, Stonehenge, to study its acoustic properties. Built approximately 5,000 years ago, the landmark in southern England has puzzled historians for centuries, but...

With sufficiently sensitive hearing and powerful equipment, if a source of music traveled past someone at twice the speed of sound, they would hear the music backward.

Tornadoes produce inaudible signals to humans hours before forming

Researchers at the National Oceanic and Atmospheric Administration have found that tornado-producing storms generate specific sounds below the range of human hearing, much like the infrasonic signals produced by earthquakes and avalanches. Although difficult to distinguish from wind noise, scientists hope to build systems that use these signals to improve tornado forecasting.

Audism is institutionalized discrimination against deaf people

Promoting the idea of hearing-at-all-costs in medical and education settings has created division in the deaf community and influenced decisions about learning sign language.