Axis Communications 210A - Manual (Page 27)

27 AXIS 210/210A/211/211A - Audio (AXIS 210A/211A only)
There are two adjustable parameters available for noise cancellation:
• Noise canceller threshold level
• Noise canceller attenuation
When the incoming sound is louder than the threshold it will pass without being affected.
When lower than the threshold, the incoming sound will be reduced by a certain
attenuation factor. The threshold level should be set higher than the background noise, but
lower than the useful audio.
The noise canceller threshold value can be set to High, Medium High, Medium low or
Low. A lower threshold will allow most audio to pass, only the weakest background noise
will be reduced. A higher threshold will make the noise canceller act on even stronger
background noise. At the maximum level - High - there is a risk of reducing useful audio
as well.
There is thus always a trade-off between noise canceling and sound quality. In other
words, increasing the noise canceller attenuation results in deterioration in sound quality.
To adjust the threshold and attenuation to an optimum level, change the levels and then
listen to the result, repeating as necessary.