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.

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.

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

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.

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.

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.

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.

Ultrasound machines emit and receive high-frequency sound waves to construct images of the body's interior, with differences in the penetrating power of different frequencies allowing medical professionals to identify different structures.

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.

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

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

Scientific applications of bubbles include logic gates, laser production, and medical imaging

Microbubbles of nonreactive gas can be administered to improve the reflection of sound waves and the resulting imaging during an ultrasound. Bouncing light waves within a bubble can stimulate emission of light from a trapped chemical, just as occurs within a laser, and bubbles can act as valves that control the flow and reaction rates in microfluidic systems.

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 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.

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.

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.

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.

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.

Acoustic Vehicle Alerting Systems provide motor sounds in electric vehicles

Since 2019, various global standards have set requirements for these systems, which seek to mimic combustion-engine sounds by meeting specific sonic criteria, including sound pressure, frequency, and pitch. Sound engineers design these systems to meet these requirements, ensuring that passers-by, particularly the blind and visually impaired, can detect the presence of a vehicle.

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.

High-frequency sound waves have been used to brew espresso with room-temperature water and about one-fourth the energy of a traditional espresso machine, which relies on hot water and pressure.

Studying 'sonic' black holes

If a fish screams as it falls down a cascading waterfall accelerating to ridiculous speeds, will his fish friends above hear him scream? This analogy, odd as it is, has become an essential tool in the astrophysicists kit for learning how enigmatic black holes operate. Lab experiments mirroring the so-called sonic black hole have achieved insights for their cosmic counterparts. Read how it works in this brief piece.