Cedar dns2000, Manual, Page: 22 / 30

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SUPPRESSING TRAFFIC NOISE AND OTHER
AMBIENT SOUND
The DNS2000 can suppress background noises such as road traffic, aircraft, air conditioning,
wind, rain, and many other common soundstage, location, and outside broadcast (remote)
problems that contaminate audio. If your signal exhibits any of these problems, you can
suppress them as follows.
First, identify the frequency range(s) in which the noise lies.
You should be able to do this by listening to the problem. However, if this proves difficult, you
can use the following method.
It is not important that you find the perfect settings at the first attempt. In particular, you will
be able to refine your Level and Band Gain settings once you have found the correct range.
Begin as follows:
Ensure that the DNS 2000 is not in Bypass
Select Full Range
• Set all six Band Gain controls to -24dB
• Move the Level control to -80 and then raise it until the noise disappears
At this point you have determined an approximate setting for the Level. This is necessary for
determining the range but it is likely that you will refine this later in the procedure.
When the Level is close to the ideal setting, you should see the Activity Bargraphs in the Control
System flicker in response to the signal content.
Now continue as follows:
• Raise the Band Gain controls to 0dB (no processing occurs)
• Adjust the Band Gain controls to suppress the noise
You should always attempt to suppress the noise with the minimum of damage to the desired
signal.
In all likelihood, you will find that the leftmost Band Gain controls are pulled down significantly,
whereas the central and rightmost are close to 0dB. This tells you that the problem does not lie
in the upper frequencies, so you should use the Range Selectors to select Low+Mid. Then repeat
the steps marked ‘•’.
If you now find that you are using all six faders in similar fashion, it is likely that the noise is
distributed across the entire Low+Mid range. However, if the suppression is still heavily biased
towards the left-hand faders, you should now select the Low range and repeat the procedure.
If you select Low alone and cannot suppress the noise, it is probable that there is considerable
noise energy in the Mid band, so you should return to using Low+Mid ranges.
For many problems such as traffic noise, the noise will lie primarily in the range 50Hz - 1.5kHz.
In this case, Low+Mid will be the correct choice.
Second, optimise the Level control.
Listening carefully to the audio, refine the Level setting so that the noise is correctly identified
without introducing audible artefacts. If this proves difficult, you can return the Band Gain
controls to -24dB for this stage.
The DNS2000 takes a short period to settle after moving the Level control (especially in the
lower ranges) so you should not adjust it rapidly.