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Journey in the Ear: Music vs. Noise



“Turn off that noise!” many a teenager, back in the day, might have heard a parent holler when playing their stereo too loud. Of course, nowadays teens are more likely to hear little outside the music they’re enjoying with their earphones.


While noise can be defined on a broad level as a sound that can be heard, it’s generally regarded as an unwanted, unappealing or non-musical sound. However, music can be subjectively experienced as noise when it is unwanted, as in the hypothetical case of the parent and teenager. Even music that one normally enjoys can be relegated to noise when it’s not wanted at that moment. One might well enjoy a live performance of Vivaldi’s, Spring, but waking up to your neighbour practicing the violin parts at 3:00 am will be experienced as noise.


But regardless of whether it is wanted at that moment, played too loud, or not a genre one cares for, music is still music. What makes it music hasn’t changed. Its structure is not impacted by the subjective context in which it is experienced. It remains technically different than noise.


There are many obvious reasons, of course, why music is appealing - its beauty, its ability to evoke or express any and all emotions, it’s comfort, its joy. There are so many obvious psychological and spiritual reasons we enjoy music.


But why do we hate noise? Why do we hate the sound of nails on a chalkboard or the drone of an engine, or the drip of a tap?

Psychological reasons aside, what makes something noise and not music?


As alluded to in the first instalment of Journey in the Ear, it has to do with math! But before we can get to that, we need to take a deeper look at sound wave frequencies. We’ve already briefly examined how frequencies produced by a musical instrument determine the pitch of the sound. For example, an “A” above middle C on a piano (A4) is typically tuned to a frequency of 440 Hz.

But sound waves are actually comprised of a bunch of simultaneously occurring frequencies!


In a musical sound wave, the primary frequency that our ears identify as a particular pitch is called the fundamental. When we hear that A above middle C on the piano, we are hearing its fundamental frequency. But there are also numerous frequencies simultaneously occurring above it, that is, at higher frequencies than the fundamental of 440 Hz. These are called “overtones”, because they occur above or over the fundamental frequency, but are lower in amplitude, thus lower in volume, than the fundamental.


Generally, naturally occurring sounds, as opposed to digitally manipulated, are comprised of multiple frequencies. The difference between a musical and non-musical sound is that the overtones produced by the individual pitches or notes of a musical instrument are always exact integers, full number multiples of the fundamental frequency. These types of overtones are called harmonics. Musical sounds have a mathematically harmonious quality inherent in the sound wave itself! Thus, the frequency spectrum, or frequency make-up, of a music sound wave contains no discordant, oddball sounds. Furthermore, these harmonic overtones occur with different intensities or amplitudes in each musical instrument, giving each instrument its own unique sound or timbre.

Noise sound waves, however, though also comprised of numerous simultaneously occurring frequencies, do not possess harmonic overtones. Rather the frequency spectrum of noise is comprised of randomness and discordant fractions. There is no harmony, or agreement, amongst these frequencies, and our brains, together with our ears, sense that. And we hate it! It’s annoying. Jarring. Abrasive. We don’t want to hear it again! Unlike musical sounds, we are not drawn to them. Rather, we are repulsed.


This is not to say that all non-musical sounds are horrible - the sound of a light rain, gentle breeze in the trees, or the tide coming in can all be soothing. But it all suggests that sounds evoke a psychological response, and we are wired for pleasing, mathematical patterns!


Let’s reward ourselves with a peak at one of those pleasing patterns right now!


The first harmonic of a musical sound wave is actually, for mathematical purposes, the fundamental, as it is 1 x (times) itself, mathematically. The second harmonic, or the first overtone (that is, the overtone occurring closest to the fundamental frequency) is always a perfect double of the fundamental frequency. In music, this is an octave. So, every time you hear A4 (440 Hz) on the piano, you’re also hearing, even if you can’t consciously identify it, hints of A5 (880 Hz, two A’s above middle C) at the same time. Wow! What else are we are hearing in that sound wave?


Find out next time as we strum deeper into the wonder of harmonics and discover how they pave the road for the journey that is music.

References:

Burg, J., Romney, J., & Schwartz, E. (2014) Digital Sound & Music: Concepts, Applications, and Science, http://digitalsoundandmusic.com/curriculum/


Glenn Elert, The Physics Hypertextbook; Chapter: Music and Noise, https://physics.info/music/

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