Music is a journey, a winding road of sound that can be both predictable and surprising, with twists and turns, peaks and valleys, speeds and colours, moods and images. A story told by sounds.
And though it springs from imagination and inspiration, music has a built-in form and structure that distinguishes it from noise. In this series, we will unpack some of the foundational building blocks of music to which our ears are attuned, otherwise known as music theory, and discover the Journey in the Ear!
Let’s begin by briefly examining sound itself. What is it? How does it work?
Simply put, sound is a type of energy, a wave of energy that our ears are able to detect and, along with our brain, interpret. Sound energy is produced when an object vibrates. Whether that’s a drum, or a vocal chord, or a slamming door, the medium around the object, such as air, also vibrates, causing molecules to bump into other nearby molecules, resulting in increased air pressure as more air molecules are suddenly jammed into a smaller, localized space, like cramming more people into an already jam-packed subway car. This is called compression.
As the air molecules rebound, a decrease in air pressure subsequently results as the molecules once again enjoy roomier spaces, or decompress. This is known as rarefaction.
One round of compression and rarefaction constitutes one cycle of a sound wave. If you’ve watched an object vibrate, you will have noticed that it shifts back and forth many times, too many for the naked eye to count generally.
The pitch, that is, how high or low the resulting sound is, depends on the number of cycles per second that occur. That is, how frequently they occur. For example, A4 on the piano, which is the A above middle C, is typically tuned to a frequency of 440 Hz, meaning, 440 cycles of compression and rarefaction, or rising and falling air pressure, per second occur to produce that pitch. Ever noticed how slowing down the speed of a recording lowers the pitch? That’s because the frequency has dropped. Conversely, speeding it up, increases the pitch. Those of us who grew up with record players will have experienced this when we played an LP (long play album) at the 45 setting instead of 33!
And though the frequency determines the pitch, striking the piano key harder does not increase the frequency of cycles, but rather the amount of energy or amplitude carried by those cycles. The greater the force with which the key is struck, the greater the energy carried by the sound wave, and thus, the louder the sound, or decibel level, as it is typically measured.
Sound emanates in all directions from its source but requires a medium such as air, water, metal or glass to transmit it, as it cannot travel in a vacuum. Though about a million times slower than the speed of light, it’s ample fast enough (about 344 metres per second by air) to reach our ears pretty much instantly if we’re near the source of the sound. However, sound waves lose energy quickly as they travel, which is why sounds we hear are very short-lived and are not heard very far.
Unless, of course, the amplitude of the sound wave is massive, such as the sound wave a lightning strike produces. Aka thunder. The high amplitude (lots of energy to create a thunderous boom) of the wave allows it to be carried several kilometres, but thankfully, we’re usually too far away to hear it instantly and have to wait a second or more for the wave to travel to us (although I, personally, have seen lighting strike close up on more than one occasion!).
Sound waves, in the course of their travel, like light, can also be reflected off of something, enabling sonar technology, which bounces sound waves off objects underwater to create an image of an object.
Even more amazingly, sound waves can put out fires! Yes, you read that right! Watch a little bit of noise do just!
Who’d have thought a bit of noise could do anything more than, well, be noisy!
Speaking of noise, what is it? What distinguishes it from music? Aside from the subjective evaluation of the sounds we hear, that is, whether we like them or not, there is actually a scientific explanation as to why music is so pleasing to the ear but noise is not. And it has to do with math! But we’ll save that for the next instalment of Journey in the Ear.
Burg, J., Romney, J., & Schwartz, E. (2014) Digital Sound & Music: Concepts, Applications, and Science, http://digitalsoundandmusic.com/curriculum/
Shaffer, K.,Hughes. B, Moseley, B., Open Music Theory; Chapter: Pitches, http://openmusictheory.com/pitches.html