Technical data
The
differences
that
you
hear
among
the
various
waveshapes
are
due
to
their
different
harmonic
structures.
A
waveshape
may
bethought
of
as a
collection
of
simple
components
called
"partials."
Most
pitched
sounds
consist
of
a
first
partial
called
the
"fundamental/'
and
other
partials
that
are
higher
and
often
not
as
loud.
When
the
frequencies
(pitches)
of
the
upper
partials
are
whole
number
multiples
of
the
frequency
of
the
fundamental,
all
the
partials
are
called
"harmonics."
(They
are
in
a
harmonic
relationship
to
each
other.)
That
is,
a
tone
with
a
fundamental
frequency
of
100
Hz
may
be
composed
of
simple
sounds
(sine
waves)
having
the
frequencies
100
Hz, 200
Hz,
300
Hz,
400 Hz,
and
so
forth.
(Whole
number
multiples
of
the
fundamental
frequency
100
Hz.)
Upper
partials
that
are
harmonic
tend
to
reinforce
our
perception
of
the
fundamental
frequency
as
the
"pitch"
we
hear.
The
presence
and
relative
strengths
of
harmonics—the
harmonic
spectrum—accounts
in
part
for
our
perception
of
the
timbre,
or
distinctive
tone
color
of
instruments.
Each
WAVESHAPE
control
provides
a
con
tinuous
selection
of
waveshapes
with
a
variety
of
harmonic
spectra,
or
arrangements
of
partials.
These
waveshapes
are
the
basic
timbral
building
blocks.
The
harmonic
spectrum
of
a
waveshape
is
often
depicted
in
bar
graph
form
as
shown
below.
The
position
of
a
bar
along
the
horizontal
indicates
the
presence
of
a
harmonic;
the
height
of
that
bar
represents
the
relative
strength of
that
harmonic.
(Relative
strengths
are
also
indicated
with
fractions
or
decimals).
The
following
graphs
depict
the
harmonic
spectra
for
some
of
the
waveshapes
available
on
the
Multimoog;
the
first
ten
partials
of
a
tone
of
100
Hz
are
depicted:
WAVESHAPE
RELATIVE
HARMONIC
CONTENT
16
"7
i/e
1.-9
,,,c
H:
0
100
200
3OC
400
SOO
600
700
BOO 900
1000
■5
J
I
0
!0O
200 300
400
^30
600
700
800
900
1000
WOE
RECTANGULAR
J_
.*
I
I
•«»
I
I •
I
i
I
Hj
0
100
200 300
400
500 600 700
800
900
1000
MARROW
RECTANGULAR
0
100
200
300
400
500
600
700
800
900
1000
Each
oscillator
on
the
Multimoog
generates
sawtooth
and
rectangular
waveshapes.
A
square
waveshape
is
a
rectangular
waveshape
whose
top
and
bottom
are
of
equal
width.
As
the
graphs
show,
the
sawtooth
/I
waveshape
has
all
harmonics;
it
is
useful
in
producing
string
and
brass-like
sounds.
The
square
waveshape
iTl
has
only
odd-numbered
(1,3,5,7,
etc.)
harmonics;
it
is
used
to
simulate
"hollow"
sounding
instruments
such
as
the
clarinet.
As
the
rectangular
wave
becomes
asymmetrical
(lop-
sided)—
|~~1_
,
f]
,
|[_
,
—
its
harmonic
spectrum
changes
in
a
complex
manner,
producing
"nasal"
sounds
useful
for
simulating
single
and
double-reed
instruments.
31