Algorithm Manual Revision 4

Backdrop
English Manual – Updated 2018-02-28 207
is often dominated by lower frequency noise. Fi-
nally, the Hiss component consists of the broad-
band noise having a relatively flat spectrum. In
the example shown in the figure the noise at
higher frequencies is predominantly due to hiss.
BackDrop allows you to selectively reduce each
of these noise components.
The MultiType model is a good choice when the
noise is made up of two or more components
or when you have noise (such as hum due to
ground loops) with clear tonal components. The
MultiType model provides six primary controls
(Buzz Aggression, Room Aggression, Hiss Ag-
gression, Max Reduction, Basilar Dispersion,
and Transient Recovery).
Buzz Aggression
Buzz Aggression controls the overall amount of
processing applied to the tonal components of
the noise. Buzz Aggression can range from 0 %
to 100 % with 0 % meaning that no processing
is being applied to the signal. The Buzz Aggres-
sion parameter works in conjunction with Max
Reduction.
Examples of noise sources with tonal compo-
nents include hum (50 or 60 Hz) due to power
lines and ground loops as well as the tonal com-
ponents due to the cyclical nature of some noise
sources such as air conditioners, cooling fans,
hard disks or CRT fly-back transformers.
Room Aggression
Room Aggression controls the overall amount of
processing applied to any broadband noises that
do not have a flat spectrum. It is an aggression
control for the colored (non-flat) broadband por-
tion of the noise. Room Aggression can range
from 0 % to 100 % with 0 % meaning that no
processing is being applied to the signal. The
Room Aggression parameter works in conjunc-
tion with Max Reduction.
Typical examples of noise sources that are tar-
geted by the Room Aggression parameter in-
clude room noises due to air conditioning units
or cooling fans, as well as the low frequency
rumble due to traffic noise or air movement in a
large hall.
Hiss Aggression
Hiss Aggression controls the overall amount of
processing applied to any broadband noises
having a flat spectrum. Hiss Aggression can
range from 0 % to 100 % with 0 % meaning that
no processing is being applied to the signal.
The Hiss Aggression parameter works in con-
junction with Max Reduction. Typical examples
of broadband noise sources having a flat spec-
trum include tape hiss and quantization noise.
The Max Reduction, Basilar Dispersion, Tran-
sient Recovery, and Link Controls function ex-
actly as in the Basic Model.
Backdrop algorithm – print page
The Print screen contains all of the controls
needed to capture the information required by
BackDrop regarding the characteristics of the
noise. BackDrop will not reduce the noise prop-
erly unless you have provided it with a suitable
noise print. This screen provides five parameters
(Capture, Calculate, Play, Trim Start, and Trim
End).
Capture
The Capture control causes BackDrop to auto-
matically capture (record) 1.5 seconds of audio
to use in the analysis of the noise characteristics.
When in play mode, capture is not available
Calculate
When Capture is pressed, the Capture button is
lit while BackDrop records 1.5 seconds of audio.
During this time the status window will indicate
that BackDrop is recording the audio. Once the
audio has been captured, the Calculate button
will automatically light up and the status window
will indicate that BackDrop is calculating the
noise print information. BackDrop takes a few
seconds to calculate the noise print information
since it is analyzing the noise data and calculat-
ing the noise print information for each of the
three models (Basic, MultiBand and MultiType).
There are often times when it is necessary to
recalculate the noise print information without
capturing new audio. For example, it is neces-
sary to recalculate the noise print information af-
ter the Trim Start and Trim End points have been
altered (see below). In this case, press the Cal-
culate button to have BackDrop update the noise