Sonic Science - Why Does My Tone Sound This Way?

The nature of sound - our new Sonic Science series   20-Oct-12

In the first in a new series of blogs from Amped blogger Jawor Iwanow, a physics major at the University of Innsbruck, Jawor discusses what 'tone' means in scientific terms, and how you can apply scientific theory to affect your tone in easy ways. This is part one of the series, an introduction to the nature of sound and how you can use it to be generally awesome, with part two (and more awesomeness) to follow...

Most musicians, but guitarists particularly, are fascinated with sound and tone. Having a signature sound is one of the many holy grails for the axe-wielders of our time and age. From my experience, I can safely assume, that most of us have consciously chosen this quest and tried to create a magical sound.

And while tone and sound do have magical aspects about them, I decided to shed some light on the mysteries. How? Through science! 

As a mathematics and physics student I've gathered knowledge about how a lot of things in this world work, but my main interest always was music. I have come to know and understand things I believe could and will help musicians create the sounds and tones they hear in their head without having to buy tons of gear and experimenting with knobs and faders for hours.

But don't you worry, dear reader, I won't allow myself to get too ”scienc-y” or too absorbed in the beauty of mathematics. But it is beautiful.  

I will try my best to make this as understandable as possible, so that those who who aren't into my scientific fields of interest can keep up and gain something out of it.

Now, you may be asking yourself, how physics and mathematics can help you understand sound, tone and your gear. If you think about it, it is obvious; the nature of sound is physical and mathematics is the language of nature.

So, without further ado, let us get to the basics:

Sound consists of sound-waves, which are actually vibrations that are carried through the air and perceived by our ear. For this to happen, the sound-wave has to have a certain frequency and a certain amplitude, for our hearing is limited (we theoretically can perceive pitches from 20Hz to 20000Hz, though our hearing gets worse with age and because of noise pollution or through hearing damage caused by loud volumes. How loud the sound has to be, to be perceived, depends on two factors; the pitch and the hearing system of the individual).

The definition of the unit “Hz” (Hertz) is the number of cycles a periodic phenomenon goes through in one second. So 440hz would mean, that the sound wave goes through 440 cycles every second. Basically every repeated movement can have it's cycles counted.

If you have a marathon runner who runs laps keeping a constant speed, you could measure his speed in Hertz; postulate the lap as one cycle (it begins on the starting line and ends on the starting line). If you runner runs 16 km/h and the lap was 800m, he would complete one lap every 240 seconds, which would be 0,00417 Hz. 

Volume, which is not loudness, to clear a misconception, is usually measured in decibel (dB). If you'd like me to, I'd explain the (deci)bel unit later, yet it will not have any real importance for us. I just add it for the completeness sake.  As for the difference; volume is measured - it is the pressure of the sound wave - loudness is “felt”, it is how loud a sound is perceived to be. If you have free time on your hands and want to learn a bit about the dark sides of music production, google “loudness war”.    

A big and common misconception is that sound-waves are electromagnetic in nature. Electromagnetic radiation (e.g. light, radio waves...) cannot be heard, but it can be transformed to audio. And, although they are different phenomena, they share certain qualities. 
What comes out of your magnetic pickup actually is an electric signal, not sound. More on this later.  

When speaking of musical sounds, we think of “organized” sounds (as opposed to “chaotic”, which we perceive as noise) and we mainly think of the pitch. A violin, a guitar and a piano can all produce the pitch of 440hz. Yet, they sound different.

Next page: A simple way to affect tone