Polycom C16 - Manual (Page 468)

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
B - 6
moving microphones closer to the talkers, moving noise sources away from
the microphones, lowering the level of the noise, and improving the acoustics
in the room to reduce the amount of reverberation. Improving the acoustics in
the room can be done by increasing the absorption of surfaces in the room -
acoustic paneling, reduced HVAC airflow speed/noise, carpeted floors,
curtains, and other absorptive surfaces wherever possible.
Microphones For Conferencing
While omni-directional microphones seem like a natural choice for
conferencing applications as fewer microphones would be required for a given
number of participants, their 360 degree pick up will pick up extra noise, room
reverberation and the remote audio from the loudspeakers. The result will be
that the signal picked up by the microphone in a conferencing environment
will sound muddier and noisier than the signal from a directional microphone.
It is for this reason that most installations use cardioid style microphones.
The style of microphone is determined by how the participants will use the
conference room. It is common in rooms where there is a great deal of
collaboration or sharing of drawings, documents, etc. to get the microphones
off the table and have them in the ceiling. This allows for much sharing of
paperwork without the concerns or complaints of the sounds of paper as it
slides across the microphone elements.
Gooseneck Microphones
In many board rooms, gooseneck microphones are used and distributed
around the table with one microphone per participant. Each of these
microphones will have a neck that takes the microphone off the table and
brings it closer to the local talker's mouth. In addition these microphones will
have a directional pattern to further improve the rejection of the ambient noise.
One consideration to remember is that some gooseneck microphones have a
tendency to straighten-out over time, so it is recommended that the
microphone positioning be checked periodically to ensure that the gooseneck
microphones are not pointed directly at loudspeakers.