TROUBLESHOOTING
VORTEX EF2211/EF2210 Reference Manual 40 Technical Support: 800.932.2774
fied by 6 dB more than necessary. This adds 6 dB to the room gain, which may
be sufficient to cause room gain problems. This situation could easily arise if, for
example, the conferencing equipment is set up so that participants are too far
from the microphone. In such a situation, after correct microphone setup the
local microphone audio level may be too low because of the distance from the
talker to the microphone. The microphone audio will most likely also be muddy
and reverberant. The installer or user may try to solve these microphone audio
quality problems by turning up the microphone amplification, thus adding to the
room gain. This problem can be remedied by proper microphone selection
(pickup pattern, directionality) and placement, coupled with proper microphone
input calibration.
3. A third common cause of room gain problems is excessive coupling between
loudspeaker audio and microphones. This can be addressed by reducing the
microphone coupling, either by positioning microphones so that their pickup pat-
terns are biased away from the loudspeaker audio (and direct reflections of loud-
speaker audio), repositioning loudspeakers, or reducing the loudspeaker
amplification.
In summary, any amplification applied between the reference input and the micro-
phone input can add to room gain problems. To avoid problems, ensure that the Ref-
erence input signal is not too low, and the microphone input signals are not too high.
Run the built-in EF2211/EF2210 Room Gain test to verify that you do not have room
gain problems (See “Verify Room Gain” on page 12).
In-Conference
Quick Check
If you experience residual echo problems during a conference, you can quickly check
that the reference and microphone levels are calibrated and not causing room gain
problems by using the Room Gain parameter (See “Verify Room Gain” on page 12).
If this excessive coupling activity level is evident on only one microphone input chan-
nel, that microphone channel should either be redirected to reduce coupling to loud-
speaker audio, or recalibrated as it will need to be turned down. If the excessive
coupling activity is observed on all (or most) microphone channels, then this indicates
either that the room audio is too loud or the reference signal may need to be recali-
brated (this will be indicated by observing low activity levels on the S
IGNAL LEVEL
M
ETER).
C
OMMON CAUSES OF EXCESSIVE
R
OOM GAIN
REMEDY
Excessive remote (reference) input
amplification
Apply enough gain to the codec, phone
or program audio inputs which will
make up the Reference input signal.
Excessive microphone amplification Select proper microphones for talker
distance according to pickup pattern
and directionality and properly cali-
brate mic input.
Excessive coupling between loud-
speaker audio and microphones
Reduce mic coupling by repositioning
mics or loudspeakers, or by reducing
loudspeaker amplification.
Table 3: Summary of Excessive Room Gain.
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