26 Fascinating Facts About Sound: It’s Not Audio “Only”

Did you know that sound can make wine taste better and even levitate small objects?

As podcasters, we know the power of sound better than most. But when you’re speaking into the mic, do you ever stop to think about those invisible waves that are formulating your words?

To celebrate our favourite medium, I’ve pulled together some of the most mind-bending facts about sound that might change how you think about – or even approach – your next podcast recording.

How Humans Listen

Children can hear sounds that adults can’t. Humans typically hear between 20 Hz and 20,000 Hz, but this range shrinks with age. Infants can actually hear frequencies slightly higher than 20 kHz, but lose some high-frequency sensitivity as they mature. High-frequency sounds (above 17 kHz) can only be heard by infants and younger people. This is why they’re used in “teen deterrent” devices.

You can hear without ears. You can “hear” sound through vibrations in your skull, which is how bone-conduction headphones work. 

There’s science behind not liking your own voice recording. If, like most people, you hate hearing the sound of your own voice during editing, there’s science behind that. You hear your voice differently because, normally, you hear it through both air conduction and bone conduction. Recordings, on the other hand, only capture air conduction.

Sound frequencies can stir emotions. Low-frequency sounds are used in horror movies because they trigger primal fear responses in humans. These sounds cause fear and anxiety, even when we can’t consciously hear them. Using low-frequency sound effects in your horror podcast will create more impact.

Sound can make things taste better. Humans naturally want to match outside sensations to taste. In one study, participants found wine tasted better when matched with the right music.

Sound underwater warps human perception. Humans find it difficult to pinpoint the direction of where an underwater sound is coming from due to different acoustic properties. The cues we usually use to determine sound direction – interaural time and level differences – are different under water due to high sound velocity of water and longer wavelengths.

Sound can be used as a weapon. During WWII, some nations experimented with using low-frequency sound waves as a potential weapon. This is called a sonic or ‘acoustic attack‘. Sonic weapons can be explicit, e.g. an extremely loud noise. Or, they can be covert, like infrasound that affects the human body without the targets noticing.

Acoustics in architecture. Ancient theatres like Epidaurus in Greece have nearly perfect acoustics. Their careful design means the audience can hear whispers from the stage even at the furthest distance.

Acoustics in Architecture: How Spaces Shape the Sounds We Hear

Read article called: Acoustics in Architecture: How Spaces Shape the Sounds We Hear

Sound can reduce anxiety and stress: The 528 hz frequency is a specific tone (roughly between a C and a C# note on the musical scale). In wellness circles, it’s thought to have healing properties. In one scientific study, when rats were exposed to the sound, it reduced anxiety and increase testosterone in the brain.

How Animals Hear

Bats use ultrasound to navigate. Bats navigate and hunt in pitch dark using echolocation, emitting sounds at frequencies above 20,000 Hz, which is beyond human hearing.

Elephants use infrasound to communicate. Sounds below 20 Hz (infrasound) can be felt more than heard and are used by elephants for long-distance communication. These sounds can be felt from several kilometres away.

Water temperature helps marine life talk to each other. In the ocean, the SOFAR channel (Sound fixing and ranging transmission) is a layer where sound travels best because it’s the right temperature. The SOFRA channel helps marine sounds carry for thousands of miles.

The Record Breakers 

The loudest sound on earth. The eruption of the Krakatoa volcano (Indonesia 1883) produced a sound heard 3,000 miles away. This makes the Krakatoa eruption the loudest recorded sound in history. But some poorly-mixed podcasts still come close with their intro music.

The fastest recorded human speech. On average, humans speak around 150 words per minute. The Guinness record for the fastest talker in the English language is over 600 words/minute.

The most intense sound ever made by nature. The tiny snapping shrimp (less than 10cm long) snaps its claws so fast to stun prey that it creates a sound louder than a gunshot (up to 210 decibels).

The quietest place. The Anechoic chambers at Microsoft’s Washington headquarters were built to absorb nearly all sound. This creates a silence so deep (-9.4 decibels) that people often can only hear their own heartbeat.

The lowest-sung vocal note. Tim Storms holds the Guinness Book of Records title for the lowest note produced by a human at G -7 (0.189 Hz). This is 8 octaves lower than the lowest G note on the piano.

The Super Sciencey Stuff 

The speed of sound varies. Sound travels fastest in solids, slower in liquids, and slowest in gases. It changes based on the medium and its properties, such as air (343 m/s), water (1,480 m/s), and steel (~5,960 m/s).

Sound can’t exist in space. Sound needs a medium (air, water, or solid) to propagate. This means that sound can’t exist in space.

Sound changes depending on your distance from it. The change in sound frequency as an object moves closer to you is called the doppler effect. This explains why a siren’s pitch changes as it passes.

Temperature impacts how sound travels. Sound travels faster in warm air than cold air because heat increases the energy of air molecules. However, sound travels further distances in cold air because sound waves bend away from warm air and back towards the ground.

The Weird and Wonderful

Resonance and glass shattering. A singer can break a glass by matching its resonant frequency with their voice at a high volume. Don’t believe it? Watch this video (skip to 6:30 if you’re feeling impatient).

Sound waves have a shape. Sound waves appear as sine waves and can be visualized using devices like oscilloscopes. They can also create patterns in sand. Cymatics experiments show how sound frequencies produce intricate patterns in particles on a surface.

Sound can lift objects. Acoustic levitation is when sound waves suspend small objects in midair by counteracting gravity.

You can create audio illusions. Like optical illusions, you can trick the human ear into hearing sounds differently from how they’re being created. For example, Shepard tones create an auditory “staircase” effect of endlessly rising pitch when, in reality, it’s just a single note.

You can put out fire with sound. With the right frequency, sound waves can seperate oxygen in fire from fuel, extinguishing a fire in seconds. Watch how these students from Virginia were able to extinguish fire using sound.

It Isn’t “Just” Sound

Sound is a fascinating and limitless medium. In its simplest form, it is perfect for talking to your audience during their commutes, dog walks, or gym sessions. Some podcasters go beyond words, too, creating atmospheres and soundscapes using ASMR, Binaural Beats, and 3D audio techniques. As we’ve learned today, too, there is just so much more to explore.

So the next time you’re behind the mic, remember this: Those invisible sound waves you’re creating are part of the same phenomenon that helps bats navigate in pitch darkness, marine life survive, and makes humans feel all different kinds of sensations and emotions. There’s something pretty incredible about that.