528E
15
recorded and reproduced levels shows requirements for tre men dous boosts, on the order of 10 to 30
dB. Aside from the subjective effects of this range, the ability to control unwanted sounds in this
range is equally important to subdue stage rumble and outside traffi c noise (especially im por tant
where there are subways beneath buildings!). Overemphasis caused by close cardioid mi cro phone
placement can cause muddiness in the overall sound; attenuating (cutting) the very-low-bass region
can greatly improve overall clarity.
Rhythm and Musical Foundation
In the bass region, most of the low, grave tones of the drum and piano can be found. Here we can
also fi nd the fundamentals of the rhythm section, as well as the foundation of all musical structure.
It was Leopold Stowkowski who said “If I had a thousand bass viols I could use them all!” This is
not as extreme as it may sound. A bass viol, even though it is reinforced by its sounding board, gen-
erally plays single notes and possesses little dynamic range. In a large orchestra, as many as eight
bass viols may be used. A total of 1000 bass viols in this case would only give an additional 21 dB
of level, which is not an inordinate amount given a glance at Mr. Fletcher’s equal loudness curves.
Pay attention to this range because the overall musical balance of your program can be controlled
by equalizing or attenuating the 100 Hz range.
Telephone Quality
The ear is reasonably sensitive in the midrange frequencies, and sound restricted to this range has
a telephone-like quality (which is generally why telephone-quality frequency response covers the
300-3 kHz range).
If you make the 6th octave (500-1024 Hz) louder with respect to the other octaves, the subjective
result is a horn-like quality. If you emphasize the 7th octave (1000-2000 Hz), the effect is one of
tinniness.
The fundamental tones in most music lie equally above and below middle C (261 Hz), from 128 to
512 Hz. As most instruments are rich in the fi rst overtones, the majority of sound energy is found up
to the 2.5 kHz range. Music editors and others engaged in listening to music over long periods fi nd
that listening fatigue can be reduced by attenuating the 5th, 6th, and 7th octaves by about 5 dB.
Lisping Quality
The 3 kHz range delivers a generous stimulus to the ear. At very loud levels the region of greatest
ear sensitivity shifts downward from 5 kHz; this is why many “PA” speakers have broad peaks in
this region. A char ac ter is tic of low-level signals peaked at 3 kHz is a “lisping” quality, and the total
inability to distinguish labial sounds such as m, b, and v.
In wide-range lower level systems, a peak in the 3 kHz region has a masking effect on important
rec og ni tion sounds, and on others which lie above 4 kHz. Brilliance and clarity are lost and without
attenuation of this region, an unconscious strain with increasing fatigue is felt according to the
amount of 3 kHz boost.
Presence Range
The usual band affecting clarity in male speech is 3000 to 6000 Hz. In a woman’s voice, the fun da -
men tals are roughly an octave higher than a man’s, and a woman’s range of consonant clarity lies
between 5000 and 8000 Hz (the high-end of this range approaches a region of hearing in sen si tiv i ty
in humans). Furthermore, the total range of a woman’s voice is about half that of a mans, stim u -
lat ing fewer hearing nerves, and for this reason, is consequently still weaker upon reception.
Wide range sounds, especially those of singing voices, have fundamentals with harmonics in the 5
kHz region of good ear sensitivity. Voices that are powerful or rich with harmonics at 5 kHz sound
especially pleasing, clear and full. Male opera singers are particularly favored with 5 kHz sounds,
women less so. In popular music, this range shifts downward somewhat. It follows that voices
defi cient in the 5 kHz range can be enhanced in listening value by a generous boost on the order of
5 to 8 dB at 5 kHz. A secondary benefi t of this boost is an apparent increase in level; a 6 dB rise at 5
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