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THE MUSICAL SPECTRUM
This
chart
correlates
familiar
musical
instruments
with the numerical
frequen-
cies that they produce.
Given
the often
talked
about
musical
range
of 20 to
20,000
Hz, it is surprising to see how
low musical fundamentals
actually are.
(Almost
all are
under
3,500
Hz.) It
Should be understood however that if all
instruments
were
perceived
only
by
their
fundamental
frequency
output
(white
areas),
they
would
all sound
alike. It is the harmonics or overtones
(Shaded areas)
that give each individ-
ual
instrument
its character
or
timbre
and set it apart from the rest.
Interestingly
enough,
the human
ear is
more
sensitive to certain octaves
in the
musical
spectrum
than
to
others.
[j=
Approximate
fundamental
range (and
lower
harmonics )
been 3 77 Approximate
mate ee of relati
vey
important
harmonics (subjective by necessi ty)
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aire
sal
seden oiia diasin pi
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HORN
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——
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TRUMPET
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| CYBAL
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peed pial oain
oo
ae:
MALE
voice
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FEMALE
VOICE
20 [30]40 [60] L420] [240]
[S00] Coool 2000]
HZ
[LJ = FREQUENCY
LEVEL CONTROLS
Whoever
designed
this engineering
marvel
deemed
it necessary
to tune the ear
more
toward
the midrange
frequencies
where
speech
and
voice
communication
occur, than to the outer octaves of low bass and high musical overtones.As a result,
very small energy
changes here will cause
a more drastic psychoacoustic
effect
that larger changes would at the frequency extremes.
In order to discuss the qualitative effects of adjustment in tonal balance, it is best to
arbitrarily divide the musical spectrum into five ranges:
The Bass (approximately 20-140 Hz). There is little musical material with fundamen-
tal frequencies
below
about
60 Hz, and
what
is normally
perceived
as low bass
material is actually in the 60-140 Hz range. The very lowest frequency control can
be used to enhance
output for the few instruments in that range (organ, contrabas-
soon,
etc.) or it can
be used
to reduce
rumble,
acoustic
feedback
and other
low
frequency
aberrations.
The 30 Hz, 60 Hz and 120 Hz controls will cause
the great-
est percepable changes in 'bass response".
The Mid-Bass (approximately 140-400 Hz). An over-accentuated mid-bass region will
yield a very muddy and "boomy"
quality to the music. A system shy of mid-bass
will sound hollow and thin. The 240 Hz control is important for good overall balance.
— 5
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