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.

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.

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.

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.

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.

Explore a visual and auditory guide to wave properties and waveforms to learn how every sound imaginable can be created by combining multiple vibrations of air.

Variations in rapidly expanding gas and mechanical elements produce fireworks sounds

Chemical compounds designed to vibrate rapidly when ignited produce whistling, screeching sounds, while crackles and pops are created by small star pellets inside the firework, which explode one after another quickly. Fluttering and chirping sounds are produced by spinning elements that rotate rapidly as the firework ascends.

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.

Fireworks make a loud booming sound after explosion due to air expanding faster than the speed of sound.

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.

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.

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.

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.

Simulate the buildup and discharge of static electricity through friction by dragging the arm and leg of 'John Travoltage' along surfaces.

Earthquakes of identical magnitudes are unlikely to cause equal damage because magnitude only measures energy released, and earthquake severity depends on environmental factors, such as local architecture and geological conditions.

Mechanical watches measure the passage of time via the vibration of a quartz crystal

When electricity from a battery passes through the crystal inside a watch, the crystal vibrates, creating an electrical signal with a precise frequency of one vibration per second. This signal moves the hand of the watch so that it ticks once per second, allowing it to track the passage of time.

The mass of a cell can be measured using hollow, vibrating beams

In 2010, scientists at MIT constructed a U-shaped device that vibrates like a guitar string with an internal fluid channel. As cells and bacteria pass through the device, its rate of vibration shifts, with greater mass creating larger shifts.

A person's voice sounds different when breathing helium, sulfur hexafluoride, or gases other than air because the speed of sound varies with the properties of the material through which it travels.

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.

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.

Some earthquakes can produce smaller tremors called boomerang earthquakes, which travel in the opposite direction and ripple back to the original earthquake's source.

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.

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.

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.

Through sonoluminescence, concentrated sound waves can produce short, high-intensity flashes of light by rapidly collapsing microscopic bubbles to temperatures up to twice that of the sun's surface.

Why atoms are used to keep track of time and define the meaning of a second

Small variations in the production of human-made devices, such as mechanical watches and pendulums, make them unreliable for the ultraprecise timekeeping required by modern technology, including financial transaction timestamping and GPS. Because atoms obey fundamental laws of nature and never wear out, their light emissions when energized provide a consistent timekeeping signal.

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.

Playing music enhances the creation, storage, and retrieval of memories

Scans of the brains of individuals who play instruments have shown enhanced connectivity between multiple brain regions—visual, auditory, and motor cortices—and the corpus callosum, which connects the two brain hemispheres. These complex connections are strengthened through practice and then used in other activities that involve both logic and creativity. The brains of musicians also appear to give experiences multiple types of memory tags, such as audio, emotional, and conceptual, improving their processing.

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.

Electromagnetic repulsion prevents objects from making contact with one another

The feeling of touching something is a sensation caused by the electromagnetic force between the electrons on the surface of objects. Since this force grows to infinity with proximity, no two surfaces can ever achieve matter-to-matter contact.

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

In Raman spectroscopy, molecules use some of the energy from incoming light to shift into a more energetic vibration and scatter the remaining light, which scientists can use to confirm the molecule's presence.

Micro-seismic activity has been produced from people cheering or dancing at sporting events, concerts, and other large gatherings, but scientists can easily distinguish these vibrations from natural earthquakes using seismometers.

Listen to the sounds of pulsars, which emit radio pulses up to hundreds of times a second

Just as figure skaters spin faster by tucking in their arms, these celestial objects acquire high rates of spin from the collapse of the cores of massive stars. The star's rotation spins its magnetic field, generating beams of radio waves from its magnetic poles. If either of these poles faces a detector, the signals can be picked up and converted to audio signals.

50 years of research has focused on unraveling the relationship between music and frisson

One insight reveals that musical passages with surprising volume changes or unexpected harmonies and beauty are more likely to trigger frisson, perhaps because they upend listeners' expectations.

Oscillating matter in the early universe left behind patterns detailing cosmic expansion

As gravity tried to bring matter closer together in the early universe, its high temperature produced an outward pressure that caused it to expand. These competing forces caused matter to vibrate and produce the equivalent of sound waves, which spread outward as the universe expanded and cooled, serving as relics of dark energy's history.

Listen to the 'sounds' of the universe with this sonification library, where astronomers have transformed certain astronomical data sets into audio for broader engagement.

Time crystals are systems of atoms organized into periodic patterns of motion

Unlike traditional crystals—whose atomic structures cause them to look identical no matter how you look at them in space—time crystals exhibit this behavior through time, where the motion of atoms will bring them to the same positions relative to one another regularly.

Microwave ovens heat food by agitating certain molecules with non-ionizing light

Molecules with resonant frequencies within the microwave range vibrate, producing heat between adjacent matter, just as hands warm when rubbed together. The mesh in front of an oven's door confines the microwaves to the container, while the rotating plate allows different parts of food to travel through regions of maximum vibration.