Where does sound come from, and how does it become music in our minds?
Music all around us
Whether we’re belting out power ballads in the shower, tapping our fingers to the radio while waiting for the traffic light to turn green, or jogging to the beat of Eminem’s “Lose Yourself” on the treadmill, we have music to thank for being a constant companion in our lives. In 2021, the International Federation of the Phonographic Industry reported that the average person listens to 18.4 hours of music weekly.
Nowadays, music is highly portable and personal. With a few gestures on a smartphone, we can listen to most songs on demand, thanks to music streaming services like Spotify. For some, it may even be as simple as saying, “Alexa, play this song.”
Technology has greatly changed the way we engage with music. Our ancestors weren’t quite as spoiled, though. Before Thomas Alva Edison invented the phonograph in 1877 – and as an extension, recorded music – music was exclusively consumed live. The only way fans could listen to their favorite musicians was through live performances with families gathered around a piano, one person on the keys and the rest singing along.
A long history of music-making
Just as the ways in which we listen to music have evolved, so too have the tools and instruments used to create and compose it. The earliest musical instrument we have evidence for dates as far back as 60,000 years when Neanderthals in the caves of Slovenia carved flutes out of the thighbones of cave bears.
But our earliest ancestors didn’t have to look far to produce music. They carried with them the very same instrument each of us carries day-to-day – the human voice. In fact, sociologists say that our ancestors created music in the form of vocalization – singing without using words – long before they began using speech. This shows how far back music-making goes in our history as a species.
What’s also remarkable is how universal music is. It exists in every society, even in the most remote corners of the world. Though music may sound different across cultures, studies show that we can infer a song’s purpose – whether for healing or dancing, as a lullaby or a love song – just by listening to short snippets of it.
Why do we like music?
What is it about music that appeals to us? Music activates the brain’s limbic system, which is responsible for emotion processing. Songs that reach an emotional peak, like Coldplay’s “Fix You,” might give us the chills, what researchers call ‘frisson.’ When we like what we’re listening to, our brain releases dopamine, a feel-good chemical also triggered by eating good food or enjoying a workout.
Besides giving us pleasure, music has the ability to soothe, energize, inspire, and bring about any number of emotions in us. Sad songs comfort us when we’re down, helping us feel a bit less lonely. Upbeat music gets us grooving, a fitting soundtrack for moments of celebration.
Music also plays to humans’ pattern-seeking behavior. When we tap our feet to the beat of a song, we’re anticipating what’s coming next. When we listen to an unfamiliar tune, our brain is subconsciously trying to create a pattern, to figure out which notes are next to come. This is a game many of us find enjoyable, whether we do it consciously or not.
What is music anyway?
Though we know music when we hear it, most people would be hard-pressed to provide a definition of it. French composer Edgard Varèse defined it as “organized sound.” By singing or playing a musical instrument, we create a combination of rhythms and melodies distinct from the noise of everyday life – the pitter-patter of rain on the window or the low hum of a washing machine.
But Varèse’s vague definition leaves more questions in its wake. What is meant by ‘organized?’ Death metal features heavily distorted guitars, accelerated drumming, and growling. Listeners new to the genre may find it highly uncomfortable to hear, but it’s still music all the same. Whether something is ‘organized’ is a judgment made by each listener, making for quite a tricky definition.
On the flip side, most people find birdsong pleasant to hear. But some scientists argue that birdsong doesn’t conform to the musical conventions humans follow and hence does not qualify as music. Yet, we still celebrate certain songs that rebel against musical norms – David Bowie’s “Space Oddity” is considered a great piece of music despite challenging existing musical rules.
The physics of sound
Music is an art form that tugs at our emotions exceptionally well. But if we pick apart the different elements that make up music, we’ll find it rooted in cold, hard science.
At the heart of music are vibrations, sound waves that travel through a medium, like air or water. Sound relies on the chain reaction set off by surrounding molecules to carry vibrations into our ears. In a vacuum, the absence of matter means there are no particles to vibrate, preventing us from hearing anything.
One important aspect of sound is ‘frequency,’ the number of waves passing through a place within a period of time. Higher frequencies produce higher-pitched sounds, while lower frequencies produce lower-pitched sounds. We measure frequency in ‘Hertz (Hz),’ or waves per second. ‘Amplitude’ refers to the loudness of a sound and is reflected by the magnitude of a sound wave. Taller waves indicate a louder sound.
The image below shows a lower-pitched sound for wave one and a higher-pitched, louder sound for wave two. A shorter distance between waves means that cycles repeat more frequently, hence a higher frequency and higher pitch.
How do we perceive sound?
Sound waves travel across space before eventually reaching our ears. For instance, when we pluck a guitar string, we set off a series of vibrations. The movement of the string causes surrounding air particles to vibrate in a similar way. These sound waves eventually reach our ears.
Perceiving and processing sound relies on two main parts of the body. The ear converts sound energy into signals, and the brain – specifically the auditory cortex – receives these signals and processes them into information we understand.
In addition to identifying what we’re hearing, the brain is able to identify where a sound comes from by comparing the signals from both ears. If a sound comes from a nearby source, it should reach both ears with the same intensity, at the same time. If a sound comes from one side, its vibrations will reach the ear closer to the source microseconds earlier than the other ear, and at a higher intensity. The brain analyzes these microscopic differences to locate the source of a sound.
Certain songs take advantage of this ability. Songs like The Postal Service’s “Such Great Heights” feed certain instruments and vocals into either the left or right channel of the stereo. This produces a dynamic and layered sound, especially when using headphones.
The brain on music
Processing sound, especially music, involves a complex set of processes across different parts of the brain. It begins with the cochlear nuclei, where the brain subconsciously process elements of sound like loudness and pitch.
The signals then travel to the auditory cortex, where processing becomes conscious. The auditory cortex performs many functions, including but not limited to determining the source of a sound, identifying frequency changes, and picking out certain sounds from a noisy backdrop.
For the brain to appreciate sound as music, auditory signals need to make several more stops throughout the brain. These signals bounce through different pathways, each with its own specialties in processing various musical elements.
The brain processes rhythm in the motor area, meaning and structure in the language area, and other elements through areas related to attention and memory. All these processes occur simultaneously, and within microseconds, our bodies will have converted vibrations in the air into something as wondrous as music in our minds.
