Noise-canceling headphones use a microphone to identify external sounds, which are then used to produce an out-of-sync version of those sounds to cancel them in your ears.

Interacting sound waves can create regions where the pressure from each wave combines, allowing objects to levitate in place against gravity or be manipulated for touch-free construction.

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.

Some sounds that have been shown to affect mood and noise have been given color names, such as brown, pink, and green noise, corresponding their frequencies to those of light.

In LIGO's interferometers, light cancels itself out in the absence of gravitational waves

The devices are designed so that a laser is split into two beams that later recombine, canceling each other out and producing no signal. Changes in the lengths of the arms due to passing gravitational waves result in an interference pattern whose properties reveal features of the objects that created the waves.

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.

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.

Notch music therapy may filter out some tinnitus frequencies

Researchers in Germany have developed a smartphone app-based therapy for individuals with tinnitus associated with hearing loss. Some people with tinnitus can use this Notch app with their hearing aids to at least partially block sound frequencies matching their tinnitus pitch—turning down the volume of their tinnitus.

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

Light waves can interfere and cancel each other out

When light waves travel past one another, their peaks and valleys combine, just as overlapping ripples in water can combine to form a larger ripple. When the peak of a light wave meets the valley of another of the same wavelength and brightness, the waves combine to produce no light.

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.

Misophonia is a neurological disorder where sounds trigger strong emotions

The phenomenon is characterized by decreased tolerance to specific sounds, such as heavy breathing, pen clicking, and water dripping, which trigger a fight-or-flight response. The resulting emotions, which can range from irritation and disgust to anxiety and fear, can be overwhelming and uncontrollable.

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.

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.

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.

Listen to the pair of colliding black holes detected by LIGO

As ripples in spacetime, gravitational waves do not produce sound, which is the perception of specific vibrations in matter (e.g., vocal cords vibrating air molecules). The "chirp" of gravitational waves comes instead from converting the spacetime ripples into sound waves that the human ear can hear.

Noise pollution from humans and technology alters animal behavior

Animals may experience chronic stress and health issues due to noise pollution, which often interferes with their mating sounds. Due to traffic, nightingales sing louder on weekday mornings, and birds near airports start singing earlier to avoid upticks in takeoffs and landings.

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.

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.

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.

See why wearing earbuds—instead of over-the-ear headphones—can cause ear infections

Earbud headphones can heighten the risk of ear infections. They can lead to earwax buildup and create a dark, moist environment as you sweat—ideal conditions for germs to thrive. Wearing external over-the-ear headphones or ones that don't enter deep into the ear canal can help.

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.

View a collection of sound animations, which depict how a source of sound waves pushes against particles to carry energy away without matter being displaced.

What to listen to if you want to focus

Have you ever put your headphones in, turned on your favorite playlist, and tuned out the rest of the world? That’s the power of music. It can improve your mood, reduce stress, and enhance focus. But what kind of music is best when working or studying? Check out this list for some suggestions.

We hear because soundwaves are converted into electrochemical signals in our ears

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.

The wave nature of matter can produce phenomena like negative time and retrocausality

Within quantum mechanics, matter simultaneously exists as both fixed particles and extended waves, allowing it to emerge across barriers—just as sound travels through walls—before it fully enters the obstacle. The resulting measurements can show that particles spent negative time within a barrier, with the future occurring before the past.

'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.

Scientists are learning to guide your dreams using sound and touch.

A cochlear implant stimulates parts of the cochlea directly, with limited pitch and timbre capabilities

People with these devices have to learn or relearn how to train their brains to interpret nerve signals as sound. The range of the type of sounds that the brain can distinguish with a cochlear implant is limited and consequently it's difficult to understand a tonal language or distinguish individual speakers in a crowd.

Some animals possess sensitive hearing to help pinpoint prey and map the world

Bats and dolphins produce sound to reflect off surfaces and create a mental image of their surroundings. Owls' faces are dish-shaped to help funnel sounds to their ears, including that of mice moving along leaves or snow. Pinnipeds, such as seals and walruses, hear in both air and water.

Holograms are produced by shining light through recordings of interference patterns

When one half of a split laser beam that was reflected off the surface of an object recombines with its other, unreflected half, the two produce an interference pattern that becomes etched onto holographic film. When light shines through the back of the film, it reacts with the pattern to create the reflected light, projecting the original object.

Try to catch the 'sound' of black holes in gravitational wave detector data

In "Black Hole Hunter," users try to listen for gravitational wave signals from black holes in four sample data files that include substantial background noise. With each level, learn more about black holes while being faced with ever-quieter signals.

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 does the cocktail party effect work?

In the 1950s, British cognitive scientist Colin Cherry started to explore how we could focus our hearing on one single source, even in a noisy environment. This video animation explains the phenomenon known as the cocktail effect and how selective hearing works. Discover how our brain is on the lookout for important or personally relevant information, even as we are occupied in other discussions.

When struck, objects vibrate at unique rates called resonant frequencies, which makes tapping wood sound different from tapping metal, but providing objects with sound at their resonant frequency can cause them to shatter.

An ear doctor with hearing loss seeks to help those with hearing loss enjoy music

Alex Chern, an ear doctor who has hearing loss himself, dreams of restoring the ability to experience "all the richness and the beauty of the sound of music" for patients—not just functional hearing. Hearing aids amplify sound waves and aren't designed to work well with music that may have varied pitch and volume. Chern is studying how hearing loss and engaging with music may affect cognitive decline.

LIGO boosts its signal sensitivity by manipulating quantum uncertainty

According to the uncertainty principle, the amplitude, or height of a wave's peak, and its phase—the point in time when the first peak is observed—are inversely linked. Based on the frequency of the gravitational waves of interest, scientists sacrifice precision in one optical property to reduce noise in another.

Neural rhythms shape how we move, focus, remember, and interact with the world

Millions of neurons in the brain produce rhythmic electrical signals, or brain waves, that guide physical movement and help form and store memories. Researchers also use these rhythms to create brain-computer interfaces, letting people control devices using only their thoughts.

Wearing a 'schizophrenia simulator,' designed to build empathy for patients, CNN's Anderson Cooper finds he struggles to function

Donning headphones that play a track mimicking the auditory hallucinations common in schizophrenia, Cooper finds he is very distracted, disconcerted, and frustrated. The auditory track aims to help listeners build empathy with patient populations by understanding the challenges they face in daily life.

A lot of jazz relies on syncopation

The style is when a musician plays a rhythm on the opposite side of the beat. That means notes are played on the "upbeats," or the spaces between the main beats of a musical bar. The effect is music that can sound unpredictable, even if it's been carefully constructed.