WHAT IS ASYNTHESIZER
Unlike other musical instruments, the synthesizer
has no fixed sound of its own. Thus, before playing it,
it is necessary to make the sounds. But with the synthe-
sizer you will be able to make, with your own hands
and by synthesizing sounds, anew type of sounds that
can never be made by any other muscial instrument.
THE THREE ELEMENTS OF SOUND
How does asynthesizer make sounds? Before ex-
plaining the arrangement of the synthesizer, let us
consider what kind of properties sound has.
Sound produced by such muscial instruments as the
piano and guitar has an interval and sound level, accord-
ing to the keyboard or chord used. It is possible to
change the intervals by changing the length of the
chord for the portion that is vibrating. In this case, the
chord's number of vibrations per second also changes.
The chord will vibrate more slowly, the lower the
interval becomes. In this way, it is possible to express
the difference in intervals by the number of vibrations
(frequencies).
Interval
Bass sounds
Treble sounds
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However, between the sounds of apiano and a
guitar, there is adifference in tone even when both
sounds are of the same interval: no one will mistake
the tone of the piano from that of aguitar. This is
because there is adifference in the way the chords
vibrate (the vibration wave form), due to the
difference in the arrangement by which the sounds
are made to generate, and because of the difference
in the shape and size of the musical instruments.
Tone difference Tone difference is reflected in wave form.
Furthermore, even when both the interval and tone
quality are the same there is adifference in sound, as
when the same key of the piano is hit in aforcible
manner and agentle manner, it would be easy to
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discern the two sounds from each other because of
the magnitude (volume) of the sound. This is because
adifference will be produced in the size and amplitude
of the chord vibrations, due to the intensity with which
the chord has been struck.
In this way, sounds produced by musical instruments
have such elements as intervals, tone and volume,
whose differences render the sound with certain charac-
teristics. These elements are referred to as '*the three
elements of sound", which may be also considered as
being the difference in the frequencies, wave forms and
amplitude.
CHANGES WITH TIME IN SOUNDS
However, the elements which render sounds with
certain characteristics are not confined to these three.
Taking the piano for example, the volume will reach
maximum the instant the key is hit, then will decrease
gradually. When the finger is released from the key-
board, the sound will fade out. In the case of the organ,
the action of depressing the keyboard will cause the
volume to rise to acertain level, which will be retained
for the duration the key is depressed. The sound will die
away when the fingeixis released from the key.
Envelope Maximum volume ^Envelope
(Such lines do not
really exist.)
K£r ON K£r OFF
Further, in such muscial instruments as the trumpet,
the harmonic spectrum changes together with the
change in volume. The tone changes too, along with
the passage of time.
Thus, such sounds as those of musical instruments
undergo deUcate changes from the time the sound is
generated to the time it fades away. The mode in which
sound changes with time is known as "envelope".
HARMONICS
What must we do in order to produce electrically
sounds that have the three elements of sound, that is,
the intervals, tone and volume, and which vary with
time (has an envelope). Before going into the matter,
let us view sound again from adifferent angle.
As regards the vibration wave forms by which the
tone is determined, it is known that any given wave
form can be measured by using the sine wave as a
measure. In other words, aU wave forms can be
analyzed into alarge number of sine waves. For ex-
ample, let us overlap, over asingle sine wave, wave
forms having an integral multiple number of vibrations.
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