Digital Sound & Music: Concepts, Applications, & Science, Chapter 3, last updated 6/25/2013
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Figure 3.7 Amplitude envelope
The combination of harmonic instruments in an orchestra gives rise to an amazingly
complex and aesthetically pleasing pattern of frequencies that taken together are perceived as
beautiful music. Non-harmonic instruments e.g., percussion instruments can contribute to
this beauty as well. Drums, gongs, cymbals, and maracas are not musical in the same sense that
flutes and violins are. The partials (frequency components) emitted by percussion instruments
are not integer multiples of a fundamental, and thus these instruments don’t have a distinct pitch
with harmonic overtones. However, percussion instruments contribute accents to music, called
transients. Transients are sounds that come in short bursts. Their attacks are quite sharp, their
sustains are short, and their releases are steep. These percussive sounds are called “transient”
because they come and go quickly. Because of this, we have to be careful not to edit them out
with noise gates and other processors that react to sudden changes of amplitude. Even with their
non-harmonic nature, transients add flavor to an overall musical performance, and we wouldn’t
want to do without them.
3.1.4 Scales
Let’s return now to a bit more music theory as we establish a working
vocabulary and an understanding of musical notation.
Playing consecutive notes in an octave (but not necessarily all of them)
is called playing a scale. There are different types of scales defined in Western
music, which vary in the notes played within an octave. These different types
of scales are referred to as intonations.
Table 3.1 lists seven types of scales divided into three general categories
chromatic, diatonic, and pentatonic. A list of 1s and 2s is a convenient way to
represent the notes that are played in each. Moving by a semitone is represented by the number
1, meaning “move over one note from the previous one.” Moving by a whole tone is represented
by the number 2, meaning “move over two notes from the previous one.”
In a chromatic scale, 13 consecutive notes are played, each separated from the previous
one by a semitone. A chromatic scale starts on any key and ends on the key which is an octave
higher than the first. This is represented simply by the list [1 1 1 1 1 1 1 1 1 1 1 1]. Note that
while 13 notes are played, there are only 12 numbers on the list. The first note is played, and
then the list represents how many semitones to move over to play the following notes.
Eight notes are played in a diatonic scale. As with a chromatic scale, a diatonic scale
starts on any key and ends on the key which is an octave higher than the first. In a major
diatonic scale, the pattern is [2 2 1 2 2 2 1]. This means, “start on the first note, move over by a
tone, a tone, a semitone, a tone, a tone, a tone, and a semitone.” A major diatonic scale
time
Max Demo:
Scale Gen-
erator
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