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Echo Canceller & Background Noise Cancellation
Feature Switches 7 & 8 on the audio matrix are used to set parameters for the audio processor in each
audio console to control how the echo canceller and background noise cancellation work. These features
are set each time the system goes through a reset. See the section "Audio Matrix Switch Settings".
Echo Canceller
When the teller speaks into the console mic the sound goes out the customer speaker, bounces off the
customer vehicle, is picked up by the customer mic and then comes out the teller speaker. In effect, the
teller hears their own voice. The echo cancellation circuitry in 5000 Series consoles is designed to
eliminate this issue. The echo canceller can have either dynamic or fixed learning. Dynamic learning
adjusts for the best possible cancellation setting while a lane is selected. Note that the console has to
sample the echo before it can attempt to remove it. For this reason the teller may hear their own voice
for the first couple of words or so while "learning" takes place. The learning time is increased as the
amount of echo changes such as when speaking to a customer in a small vehicle (not much echo)
followed by a customer in a panel van (lot's of echo). Deal drawers are also the most problematic for
echo because sound bounces back and forth between the vehicle and the building/window. Another
point to consider is that the audio processor will have a much more difficult time canceling echo if it is
overdriven. This happens when volume settings are too high or when speaking too close to the
microphone. This will also cause undesirable artifacts in the audio such as static or cutting out of the
customer's voice that may not clear up until the lane is canceled and then re-selected. Fixed echo
canceller learning is not recommended with 5501 Series consoles.
IMPORTANT: For the audio processor / echo canceller to work properly it is necessary that the lane
microphone wire pair be properly shielded from the matrix to the lane. See the sections "Cable
Considerations" and "Matrix / System Wiring Diagram" for more information.
Background Noise Cancellation
Background noise comes from a variety of sources with the most common being vehicle noise at the
customer lane and general traffic noise from a nearby street. The background noise filtering in 5000
Series consoles works well to reduce constant and consistent sounds (i.e. idling vehicles) but has more
trouble when the noise is constantly changing, such as traffic noise. This type of noise can cause a side
effect in the audio processor that most people describe as an underwater or gurgling sound. Vehicles
sitting in front of a deal drawer have also been known to cause this symptom at some locations due to
the sound bouncing between the building and vehicle but this may not occur with all vehicles. The
symptom gets worse as the gains on the matrix pots are increased, the volume adjustment on the console
is increased, or the level of the background noise increases.
Even though background noise cancellation works fine for most installations there are locations it may
be preferable to turn it off. If the drive-in is very close to a busy street for example, the watery sound
may be excessive. Keep in mind that while turning background noise cancellation off will get rid of the
"watery" sound it will also allow all background noise to be heard, including a noisy vehicle at the lane.
Regardless of the default setting from the matrix, background noise cancellation can be toggled on or off
on a console by console basis with all 5501 Series consoles and most 5001 Series consoles (rev. 3.1 &
higher). On all but the 12-lane version of the 5501, pressing the Noise Cancel button toggles this feature
on (green LED) or off (red LED). The Noise Cancel button even works while a lane is selected. With the
toggle the feature which is indicated by the LED's for lanes 1 & 3 or 1 & 2 (green = on & red = off).
Changes of this feature made from a console only apply to that particular console and will always revert
back to the current setting of dip switch 8 from the matrix whenever the system goes through a reset,
such as following a momentary power outage. For this reason the technician should select the dip switch
setting that corresponds to the most common setting used by the tellers.
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08-315 (3/6/12)
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