Korg 01/W pro - Page 20

OSC VDA
Basic Tone and Pitch Volume
| The element of volume in sound synthesis |
Let's begin our discussion of these three elements with the concept of
“volume”. Even though we use the word volume, when it comes to
sound synthesis we are not talking about simple loudness. The
sound of a piano can be recognized as such whether you're listening
to someone play it nearby, or whether you hear it coming from an-
other room down the hall. So if loudness doesn't help to distinguish
between different sounds, what does?
You are probably able to distinguish between, say, a flute and the
electronic chime that you hear when you dial to get the correct time.
However, if you check the shape of the sound waves produced by
these two instruments using an oscilloscope (that is , if the air vibra-
tions caused by the two instruments are converted to an electric sig-
na! that produces a visible wave pattern on an electronic display), you
will find that they are nearly the same.
If sound only consisted of waves in the air, it might seem odd that you
can tell these two instruments apart. The fact is that the two sounds
differ in the way that their volume changes over time, as the following
diagram shows. |
20
FLUTE
ELECTRONIC CHIME
The two instruments probably look something like this. Since the vol-
ume levels of these two sounds change differently over time, human
beings recognize them as coming from completely different sources.
Sounds such as the electronic chime which grow quieter over time are
' Called attenuating sounds, whereas sounds which remain constant,
such as that of the flute, are called continuous sounds. Try to change
the electronic tone so that it's volume changed as shown in the upper
diagram, it would sound very much like a flute.
The sound of every instrument has its own way of changing over time.
This is one of the characteristics that defines the instrument's sound.
When you are creating new sounds, too, volume will play an important
role. Here are some more diagrams illustrating how the volume of
sounds produced by a number of instruments change over time. Try
imagining their sounds as you look at the diagrams.