Comdial 8012S User Manual page 142

Note: Pressing any button (mute, hold, etc.) on the speaker-
phone while in full-duplex mode causes the system to perform
the "speech training" test again. For example, if you press
MUTE while in full-duplex mode, when you release the call
from mute, the system will perform the entire "speech train-
ing" test.
To maximize the usefulness of your full-duplex speakerphone, take
note of these following observations about full-duplex speakerphone
operation.
• The full duplex operating mode requires a small amount of time
to adapt to changes in echo; therefore, you should avoid making
any movements in the vicinity—about a one-foot radius—of the
speakerphone.
• There are certain echo limits beyond which the speakerphone
cannot effect canceling. These limits are as follows: room
echoes beyond 39 milliseconds (standard configuration) and
line echoes beyond 24 milliseconds (standard configuration).
• The speakerphone may automatically reduce the volume in each
direction when both you and the distant party talk at the same
time (double-talk). This volume reduction is necessary to
control the echoes at high volume levels. It is possible for
surrounding conversations and other sounds to trigger double-
talk even when you are not speaking. This condition may lower
the loudspeaker volume at your speakerphone.
• You must adjust the loudness of your voice to match that of the
distant party's voice. This action is necessary to cause full-
duplex operation to take place. Sustained double-talk or
excessive echo may cause the speakerphone to drop back into
half-duplex operation. This happens because the
speakerphone's echo cancel circuits cannot adapt during the
double-talk situation.
132 Comdial October, 02