4/1/11 - notes vs. noises

In today's excerpt - defining the difference between musical notes and ordinary noises:

"Every day you will hear millions of sounds and only a few of them will be musical notes. Usually, musical notes are created deliberately from a musical instrument, but they can be produced in non-musical situations -- when you 'ping' a wineglass or ring a doorbell, for example. Whenever and however they are produced, musical notes sound different from all other noises.

"What's the difference between a musical note and any other sort of noise? Everyone you know will have some sort of answer to this question, but most of them will be based on the idea that musical notes sound ... er ... musical and other noises are ... er ... not musical. ...

"If you throw a stone into a flat, calm pond you will disturb the surface of the water and create ripples which travel away from the initial splash. Similarly, if you click your fingers in a quiet room, you will disturb the air and ripples of disturbance will move away from your hand. In the case of the stone in the pond, the ripples involve a change in the height of the water and our eyes can clearly see what's going on: the height of the water goes up-down-up-down-up-down as the ripples travel away from the splash.

"When you click your fingers (or make any other sound, including a musical note), the sound ripples traveling toward your ears involve changes in the pressure of the air. We can't see these ripples but our ears can hear them. When the ripples reach our ears, the air pressure goes up-down-up-down-up-down and this makes our eardrums go in-out-in-out-in-out at the same rate -- because our eardrums are like tiny, flexible trampolines, which are easily pushed in and out by changes in the air pressure. Your brain then analyzes the in-out movement of your eardrums and decides what's going on -- is it time to run away or time to order dessert? ...

"If we could see the pressure ripples of these non-musical sounds, we would notice that they were very complicated. ... The noise ripple shape [of, for example, a door closing], which eventually arrives at the eardrum, is extremely complicated because it is made up of a chaotic group of individual ripples, which have no relationship to each other. This is true of all noises which are not musical notes. 

"Musical notes are different from non-musical noises because every musical note is made up of a ripple pattern which repeats itself over and over again. ... To be a musical note, it doesn't really matter how complicated the individual ripples are, as long as the pattern repeats itself. Our eardrums flex in and out as the pressure ripples push against them. However, our eardrums can't respond properly if the ripple pattern repeats itself too quickly or too slowly -- we can only hear patterns which repeat themselves more often than twenty times a second but less often than 20,000 times a second.

"Musical notes don't need to be made by musical instruments, in fact, anything which vibrates or disturbs the air in a regular way between twenty and 20,000 times a second will produce a note. High-speed motorbike engines or dentists' drills produce notes. In the song 'The Facts of Life,' the band Talking Heads uses what sounds like a compressed air-powered drill to produce one of the notes of the background accompaniment. This combination of music and engineering fits well with the lyrics, which compare love to a machine.

"Musical instruments are simply devices which have been designed to produce notes in a controlled way. A musician uses finger movement or lung power to start something vibrating at chosen frequencies -- and notes are produced."


John Powell


How Music Works: The Science and Psychology of Beautiful Sounds, from Beethoven to the Beatles and Beyond


Little, Brown and Company


Copyright 2010 by John Powell


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