BSS Audio OPAL Series DPR-944 Owner's Manual - Manual (Page 33)

33
11.3 De-essing, De-
popping &
reducing proximity
effect
A common problem encountered when amplifying the human voice is the
large amount of high frequency energy, heard as the sibilant ‘sss’ sound. These
high frequency or sibilant sounds can reach levels considerably greater than
the normal voice level, and can result in distortion. Selective high frequency
compression can be used to help control this. High frequency compression is
generally called de- essing, as it removes the ‘sss’ content from the program.
The DPR 944 can provide this capability by removing the sibilance with either
a bell or shelf shaped characteristic. Simpler ‘de-essers’ merely compress the
whole signal when they detect sibilance.
Depress the side chain listen switch and tune in the sibilant sound with the
frequency and width controls; you may find it easiest to start with a wide
width setting, gradually homing in on the sibilance. Release the side chain
listen switch and rotate the threshold control anticlockwise until the below
threshold meter is just fully illuminated on the normal signal peaks. Starting
with the ratio control set to 3 o'clock, notice that when a sibilant sound is
encountered, the gain reduction meter starts to indicate. The frequency,
width, threshold and ratio controls can now be fine tuned to achieve the
desired effect. Gain compensation will not normally be required when de-
essing, although operating the fast release switch might sound more
appropriate.
Setting the controls as described above will remove a ‘bell’ shaped section
from the signal as selected by the frequency and width controls. For some de-
essing applications, removing a ‘shelf’ might sound more appropriate. When
de-essing, it can be necessary to remove the harmonics of the sibilance,
which occur at higher frequencies. This can easily be achieved by setting the
frequency control higher than the sound and making the width wider to move
the effective frequency down. If the offending sibilant frequency is dialed up
on the front panel, and then the width widened to catch the higher harmonic
frequencies, the lower side of the bell will remove lower frequencies which
do not need compressing (refer to figure 11.2). To compensate for this, the
frequency - f
o
- can be set higher to move the lower slope of the bell up. The
high slope then also moves up, above 20kHz, which effectively creates a
'shelf', although in reality it is still a 'bell'.
Fig 11.1 De-essing a
signal