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.

Why helium mixtures are used in respiratory medicine

Unlike the air near Earth's surface, which is primarily composed of oxygen and nitrogen, heliox is composed entirely of oxygen and helium. Because helium is lighter than nitrogen, the lungs do not have to work as hard to push air, easing the uptake of oxygen via a ventilator, mask, or nasal tube.

Why you may hate the sound of your voice

It's a relatively common experience to cringe while listening to a recording of your own voice. This Popular Science article offers physiological explanations for the discrepancy between what we hear when we speak versus what others hear. The piece also expands on the psychology behind this discontent, and how our voices influence our self-perception and social interactions.

Professional vocalists explain the mechanics of singing

Ever wonder how your favorite singer hits those high notes? Have you been amazed at someone bringing down the house at karaoke? The secret behind singing is that it's more technical than most realize. In this video, a handful of professional vocalists break down the basics to demonstrate how you can develop a more musical voice.

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.

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.

The features that make our voices unique

Human voices are about as unique as fingerprints: similar instruments but with endless variations. We each produce sound in the same physiological way, but when we talk we’re dropping clues about who we are, what we do, and where we’re from.

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 physics behind opera singing

How can opera singers project their voices to audiences in huge auditoriums without using microphones and overpowering the orchestra? This video explains this phenomenon, using animation to demonstrate the physics of the human voice and how opera singers hone their technique to hit higher frequencies and a distinctive ringing timbre known as their squillo.

By igniting flammable gas in a tube filled with holes and playing music into it, the fire will take the shape of the sound waves, enabling the visualization of audio.

How specialized oxygen mixtures like heliox enable deep diving without feeling drunk

Beyond a depth of about 30 meters (98 feet), if divers are breathing surface air, which is about 78% nitrogen, underwater pressure forces more nitrogen into the bloodstream and induces nitrogen narcosis, whose symptoms resemble alcohol intoxication. Through saturation diving, where nitrogen is replaced with helium—an inert gas—deep divers can maintain cognitive function while working for extended periods.

You may be better at spotting a lie when listening to a speaker's voice inflections rather than watching for facial and body cues.

Once cooled to temperatures just above 2 Kelvin, helium atoms exhibit a quantum property that removes internal friction, allowing the fluid to climb up walls.

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.

Ambient sounds on Mars are lower-pitched and more muted than those on Earth

The planet's thin atmosphere absorbs higher frequencies, and audio captured by the Perseverance rover from the Ingenuity Mars helicopter revealed that sound waves travel farther than previous atmospheric models suggested.

A standard glass of champagne poured straight down releases about a million tiny carbon dioxide bubbles, according to two decades of research by a French physicist.

Billie Holiday's distinctive vocal technique was aided by new microphone technology, which allowed for quieter singing.

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.

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

Why stories about helium 'running out' indicate market volatility rather than scarcity

Only a few locations on Earth contain natural gas reserves with sufficiently high helium concentrations to make their extraction commercially viable, and geopolitical conflicts in these areas significantly affect helium production. This makes cost a major impediment to helium availability, particularly for scientific research, amid growing demand and ongoing depletion of reserves that took billions of years to form.

What did Ötzi the Iceman sound like?

The natural pitch of a person's voice depends on the size of their larynx, also known as their voice box, and the length and thickness of their vocal folds or vocal cords. Using this information, scientists have recreated the voice of Ötzi the...

Learn how helium is used in the US, the world's largest producer of the noble gas

About 44% of the global supply comes from the US, as much as the next two biggest producers—Qatar and Russia—combined. According to the US Geological Survey, more than half of this helium is used in scientific and engineering equipment (22%), non-welding-related manufacturing and fabrication (17%), and as a lifting agent (17%).

Why the ratios of helium isotopes are analyzed to investigate ocean circulation

Volcanic activity on the seafloor produces high ratios of helium-3 to helium-4, which can be tracked in ocean samples more easily than other elements because helium is nonreactive. Water from deep ocean currents can also be distinguished from air-exposed surface water sources by comparing these ratios, since atmospheric helium ratios are much lower.

An overview of helium, the nonrenewable resource that's lighter than air

The second element in the periodic table naturally forms deep underground over the course of billions of years through the decay of radioactive elements, but it is used and lost to space at rates faster than it is generated. Because of this and its extensive applications in scientific technologies, scientists continue to seek avenues for its exploration, storage, and recycling.

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.

How Stephen Hawking’s voice became iconic

Stephen Hawking relied on a voice synthesizer after losing the ability to speak due to complications with ALS. Despite technological advances, he refused to change the "Perfect Paul" voice, making it a cornerstone of his public identity.

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

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.

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.

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

How geometry and uneven charge distribution make some molecules greenhouse gases

Molecules vibrate and rotate with different frequencies based on their elemental composition and shape, which can produce uneven distributions of electrons, as seen in carbon dioxide and water. The resulting unbalanced electric field can interact with electromagnetic waves of the same frequency, causing the molecule to absorb the radiation.

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.

How helium greatly improves the efficiency of barcode-scanning lasers

Rather than directly energizing neon atoms, electrical discharge at lower, more practical power levels can excite helium atoms to energy levels nearly equal to those in neon atoms. Within a helium-neon laser, these gases are present in a 10-to-1 ratio, enabling helium to efficiently transfer energy to neon, which is then discharged as red light.

The composition of magma affects the explosivity of volcanic eruptions

Silicate-rich magma contains extensive molecular chains that trap dissolved gases like water and carbon dioxide. These gases build pressure until they violently escape, creating explosive eruptions. Low-silica magmas produce gentler eruptions categorized as effusive.

Operatic singing involves a number of different vocal personalities

Opera singing ranges are typically categorized by gender and then further subdivided into specific voice types like bass, baritone, tenor, mezzo-soprano, countertenor, and soprano voices. From the lowest to highest range, experience the difficult and impressive singing styles.

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

The outermost shell of electrons in an atom dictates how it bonds to other atoms, including those of the same element, and the properties of the materials composed of those atoms.

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.

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.

Some marine life can survive the extreme pressure of the deep ocean because of specialized molecules that strengthen proteins, enzymes, and cellular membranes.

The industrial methods for recovering helium, including filters and cryogenic separation

Membranes with microscopic pores of varying sizes can be used to selectively filter out components of natural gas, including helium, which can then be concentrated. Because helium requires the lowest temperature of all elements to condense into a liquid, extracted natural gas can also be cooled until only helium remains as a gas.

Listen to recordings of different fish species

Scientists have captured and curated this collection of species-specific recordings, helping us gain a deeper understanding of underwater ecosystems. Uncover their sounds, which include a lot of thumps, burps, and grunts.

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 helium helped preserve the US' founding documents, but was later replaced

In 1951, the Charters of Freedom were stored in glass and metal cases filled with helium, which would not chemically react with the documents. After microscopic cracks were identified in the glass through which helium could leak out of and—experts feared—pollutants could infiltrate, new encasements made of aluminum, titanium, and argon replaced the old system in 2003.

Crackling, popping, and rustling sounds have been reported during auroras

At the altitudes where auroras take place—between 100 and 300 kilometers (62 to 186 miles)—air is not dense enough to efficiently vibrate and carry sound waves to the ground. However, one theory suggests that the geomagnetic energy behind auroras can trigger electrical discharges near the surface, which may be the cause of reported sounds.

An expert recreates the voice of a 3,000-year-old mummy

Ear, nose, and throat expert David Howard discusses how his research team extracts vocal folds from preserved human tissue, which allows them to model the deceased person's larynx. From there, they can create a synthetic voice based on the organ's geometry.

Helium formation, from radioactive decay inside Earth to nuclear fusion within stellar cores

Over the course of billions of years, uranium and thorium undergo alpha decay, producing helium nuclei—two protons and two neutrons—which become helium atoms after gaining two electrons. This helium becomes trapped in underground reservoirs along with other gases and can be recovered during natural gas extraction.

Listen to samples of 'sounds' produced in the sun's interior, created from the sonification of internal vibrations detected by the Parker Solar Probe.

Solar activity and the density and chemical composition of the air affect auroral colors

Oxygen atoms can emit red and green light when energized by collisions with the solar wind, but red takes longer to be emitted and is disrupted by bumping into other molecules. This causes red light to appear at higher altitudes, where the air is less dense. Higher-energy solar wind can penetrate to lower altitudes and collide with more abundant ionized nitrogen, which produces blue light.

As of 2025, the US and Qatar dominate global helium production

The US's 42.6% share includes helium imported from Canada and refined within the states. Geopolitical conflicts can cause supply disruptions that impact several advanced technologies, including semiconductor manufacturing, aerospace systems, and medical imaging.

The properties of helium, which has the lowest boiling point of any element

The colorless, odorless, mainly unreactive element condenses from a gas into a liquid at -268.928 degrees Celsius (-452.07 degrees Fahrenheit)—near the lowest theoretically possible temperature—allowing it to serve as a liquid coolant in machines without the risk of causing damage as a solid.