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Ambient Noise Compensator
sjabek
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Is there a procedure that to setup a ambient noise compenstor. I have also been looking in the help file for ambient noise compenstor and have been unable to find anything. Where in the help file should I look ambient noise compensators.
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Ambient Noise Compensator
Allows the level of an announcer (or other programme material) to 'ride' on the average background (ambient) noise level so that the programme is kept at an audible level above that of the ambient noise.
It does this by measuring the level of the ambient noise (using a suitably placed microphone), and controlling the gain of the programme channel accordingly.
Since the gain must be controlled only by the ambient noise, and not by the level of the programme itself, the ambient signal level will only be measured and the gain adjusted during periods of inactivity in the programme channel.
The length of the gap in programme required for sampling to occur is adjustable to allow for reverberation on the programme.
Various controls further allow the user to vary the announcement threshold level for gap detection, the minimum and maximum applied gain, the speed of gain change, and the reference ambient level.
Inputs and Outputs
Announcement (Programme) input
Ambient input - labelled 'Ambient'
Audio output
Control Panel
(Ambient) Threshold control
Adjusts the ambient signal level at which unity gain will exist.
The amount by which the announcement channel gain is increased is equal to the amount by which the ambient level exceeds this threshold.
Lower threshold settings will tolerate lower ambient signal levels before increasing the announcement gain.
To lift the announcement out of the ambient noise more, reduce the setting of this control.
Ambient Level Meter
Displays the current ambient noise level. It's positioning next to the Threshold control shows the difference between the ambient level and the threshold, (which is equal to the applied gain).
Announcement gain meter
Indicates the current announcement channel gain. This also operates when the ANC is bypassed giving a visible indication of what the applied gain will be when bypass is disengaged.
Min Gain control
Determines the minimum gain that will be applied to the announcement channel.
This should be set (with the aid of the Min Gain button) during quiet ambient levels so that an adequate announcement level is obtained.
Min Gain button
Forces the gain to the minimum setting for set-up purposes.
Illuminates when activated.
Max Gain control
Determines the maximum gain that will be applied to the announcement channel.
This should be set (with the aid of the Max Gain button) during high ambient levels such that sensible operating levels, free of distortion etc. are maintained.
Max Gain button
Forces the gain to the maximum setting for set-up purposes.
Illuminates when activated.
Speed control
Determines the speed at which the gain will change. Obtrusiveness will be minimised at slower speed settings, although responsiveness to sudden changes in ambient level will be reduced.
Gap Time control
Determines the amount of time the announcement channel must be 'silent' in order for the ambient channel to be sampled.
In highly reverberant environments, a long gap time may be required to avoid false gain changes because of measuring the reverb tail of the announcement, rather than the ambient noise level.
Use the Ambient Meter as a guide to how quickly the signal dies away after an announcement ends.
Gap Threshold
Determines the announcement input signal level below which the announcement channel signal must drop before it is considered to be in a gap, and thus allow ambient level sampling.
Try setting the Threshold control 10dB or so above the idle noise of the announcement channel.
Gap LED
Informs the user when there is an announcement gap that is allowing ambient signal sampling to take place.
Bypass button
Removes the processor from the signal path.
Use bypass to set up the nominal announcement level.
[edit]Notes
The ambient microphone should be connected to an analogue input on a BLU-80 or BLU-16 Signal Processor.
The input gain should be adjusted to achieve a sensible operating level.
When setting the Ambient Threshold control, the input gain should be taken into account.
The Ambient microphone should be positioned clear of non-representative sources of sound and, to prevent tampering, preferably a place not accessible to the public.
In a large environment, several microphones could be used with a mixer object in Soundweb to get an average of the levels.
! This object is capable of raising signal levels beyond the clipping point, so care should be exercised when using positive Maximum Gain values.
! It is recommended that a Limiter be used on the output of the Ambient Noise Compensator so that short term high-level signals are not allowed to pass through to the output.
This is interesting. When will it be available for us mortals?
Cheers
Neil
Now you know as much as I do.
Dan