What is Sound?
The Ontarion office is usually a relaxed, calm, and productive environment, until one of our esteemed writers or editors asks a metaphysical question. As the writer of “Science Avenue,” I try to make a habit of staying up-to-date with the more complicated scientific and technological questions of the day, and, as the writer of “Science Avenue,” I have a habit of making myself seem smarter than I really am. Therefore, when an editor asks whether trees in uninhabited forests produce sound, I usually swoop in suggest in my most knowing tone, “Sound is a vibrational wave that propagates through mediums like air or water, but for something to be heard, one must first receive through waves.”
My definition is arrogant for two reasons. First, it suggests that I’m so intelligent that I can answer complicated metaphysical questions. Second, it’s actually a complex combination of two different understandings of sound: a physical and physiological/psychological understanding.
How does Sound work?
Sound as modern physicists understand it is an oscillation that propagates through a medium. Sound is very much a wave, and sound itself has a specific speed at which is propagates. In fact, sound has multiple speeds, depending precisely through which medium it moves through. In air, the speed of sound is approximately 340 metres per second. In water, the speed of sound is almost three times greater than that of air: 1482 metres per second. In a vacuum—like space—the speed of sound is 0 metres per second. After all, in space, no one can hear you boogie.
The speed at which sound moves through a medium is entirely dependent upon the medium in question, as well as the density, viscosity, and even the speed at which the medium is moving. Sound is a wave, meaning that it can be reflected, refracted, and attenuated. Pure tones—individual musical, for example—are perfectly shaped sinusoidal waves, whereas complex sounds form ethereal, complex patterns.
There exists, however, a complex relationship between the source of a sound and the reception of sound. According to basic sensation and perception psychology, for sound to be real, it must be sensed by a receiver, and perceived or interpreted. Animal ears receive sound—sensing the presence of combinations of tones. Animal brains perceive sound—differentiating between intricate combinations of noise to distinguish patterns of speech, growls of predators, and even music.
Physics disagrees with the physiological definition, because sound waves as defined by physics do not require a listener. Make no mistake, sound is a physical phenomenon present in our universe. Much like light and arguably time, sound is not a human social construct, but a very real part of our universe. The argument that the sensation and perception of sound is necessary for sound to be real, however, is a human construct.
Why is Sound important?
Much like all complex physical constructs, merely increasing our understanding of sound is important for the combined encyclopedia of all human knowledge. Understanding how sound works also allows the human race to answer the question: what is sound? Moreover, understanding the underlying mechanisms of sound allows us to determine whether we can call sound a “real” construct.
For the sake of simplicity, however, sound as a perceivable sensation is essential for the survival of those creatures capable of perceiving it. Organisms evolved acoustic receptors because our environments provided ample reason to be able to hear sound. Most importantly, organisms evolved acoustic receptors because sound is clearly a prevalent part of our universe.
What is the future of Sound?
Most humans can hear sound, but within a certain range of frequencies. Dogs and bats can hear greater ranges of frequencies, while humpback whales and elephants produce detectable sounds at frequencies well outside the range of human perception.
However, even those without functioning receptors can still feel sound. Sound is a construct that surrounds and penetrates the farthest expanses of the universe. As a species, we’ve developed tools that allow us to channel the potential of sound.
Once again, I propose abject idealism: how cool would it be to be able to hear what whales hear? Or what dogs hear? For now, however, I suggest an answer to the question: if a tree falls in a forest and nothing is there to hear it, does it make a sound? The solution: it all really depends on who you ask.