stereophonic AK-900, Assembly And Instruction Manual

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Fundamentals of Music
What is Music? Music is when vibrations (creating sound waves) occur in an orderly and controlled manner
forming a pattern with their energy concentrated at specific frequencies, usually pleasant to listen to. Noise is
when the vibrations occur in an irregular manner with their energy spread across a wide range of frequencies,
usually annoying to hear (static on a radio is a good example). Notice how some people refer to music that they
don’t like as noise.
Another way to think of this is that the ear tries to estimate the next sounds it will hear. Music with a beat, a
rhythm, and familiar instruments can be thought of as very predictable, hence we find it pleasant to listen to.
Notice also that we always prefer familiar songs to music that we are hearing for the first time. Sudden, loud,
unpredictable sounds (such as gunfire, a glass breaking, or an alarm clock) are very unnerving and unpleasant.
Most electronic speech processing systems being developed use some form of speech prediction filters.
Take a piece of string or rope roughly 4 feet long and tie one end of it to a chair or other piece of furniture. Swing
the other end up and down so that you have a cyclic pattern, as shown:
-4-
Now swing it three times as fast (three times the frequency), to produce this pattern:
Now try to swing it five times as fast (five times the frequency), to produce this pattern:
Since the later patterns are frequency multiples of the first, we refer to them as
overtones (the music term) or
harmonics (the electronics term) and the original pattern is called the fundamental. If you could combine all
three of the above patterns onto the string then you would get a pattern which looks like this:
This combined pattern (a single fundamental with overtones) is called a tone (and a pure tone is a single
fundamental with no overtones). Notice that each pattern is more difficult to produce than the one before it, with
the combined pattern being quite complicated. And also notice that the more complicated patterns are much
more interesting and pleasing to look at than the simpler ones. Well the same thing applies to sound waves.
Complex patterns that have many overtones for each fundamental are more pleasant to listen to than simple
patterns.