Plena feedback suppressor uses a powerful DSP with a revolutionary
patented algorithm to supress acoustic feedback. It eliminates
feedback by actively filtering out the unwanted room reverb
that leads to feedback using an echo cancellation and de-reverberation
algorithm. By adding masked, inaudible noise to the output
signal or by shifting the frequency of output signal by 5Hz,
the Plena feedback suppressor is able to detect the reverb
component of the signal and remove it before feedback occurs,
leaving the original signal intact.
The adaptive filter can be switched between fast mode and
accurate mode. The fast mode is for situations where the microphone
position changes over time, like in a discussion system with
multiple switching microphones. The accurate mode is for situations
with a fixed microphone position, such as on a pulpit where
the acoustic environment is more stable. The adaptive filter
is allowed to converge more slowly to suppress the reverb
components even more. Depending on the acoustic environment
and the chosen mode of operation up to 12dB of additional
gain is possible before acoustic feedback occurs.
Plena feedback suppressor also features a built-in automatic
mixer for the two microphone inputs. In many situations, like
on a rostrum or a pulpit or conference table, the microphones
are used to better capture the voice of a moving speaker,
although this often increases the risk of acoustic feedback.
To counter this, the automatic mixer in the Plena feedback
suppressor automatically reduces the gain of the microphone
with the lowest signal input and increases the gain of the
microphone with the highest signal input. This way it 'tracks'
the moving speaker for optimum speech intelligibility, and
the maximum feedback margin is maintained by keeping the summed
gain constant. Even when the feedbacksuppressor is switched
to 'bypass', the automatic mixer function remains operational.