Polycom EF2241 manual In-Conference Quick Check Excessive Microphone Amplification

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TROUBLESHOOTING

In-Conference Quick Check

Excessive

Microphone

Amplification

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 inputs 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 EF2241 Room Gain test to verify that you do not have room gain problems (See “Verify Room Gain” on page 14).

COMMON CAUSES OF EXCESSIVE

REMEDY

ROOM GAIN

 

 

 

Excessive remote (reference) input

Apply enough gain to the codec, phone

amplification

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 inputs.

 

 

Excessive coupling between loud-

Reduce mic coupling by repositioning

speaker audio and microphones

mics or loudspeakers, or by reducing

 

loudspeaker amplification.

 

 

Table 3: Summary of Excessive Room Gain.

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 14).

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 SIGNAL LEVEL METER).

For the EF2241 to adapt effectively, saturation (overload or clipping) must not occur at the A/D converter supplying the microphone input. Saturation introduces nonlin- ear signal distortions into what the AEC expects is a linearly echoed version of the remote speech.

© Polycom, Inc.

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VORTEX EF2241 Reference Manual

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Contents Vortex EF2241 Reference Manual Page Introduction Introduction Welcome How to Use This ManualProduct Registration Product FeaturesProduct Inputs Outputs Remote Control What’s Not Included PRE-INSTALLATIONTools Needed for Installation What’s IncludedEF2241 Front and Rear Panels PRE-INSTALLATION North American Requirement InstallationConnecting the EF2241 to Other Equipment Mounting the EF2241Codec Typical EF2241 ConnectionsDevice IDS on the EF BUS Connecting Multiple Vortex DevicesTerminating the EF2241 Factory Default Settings PresetOff Pick a Standard Signal Level Presets Multiple Vortex DevicesCheck Surrounding Equipment Configure Program Audio Sources Integrating the EF2241 Into Your System Input SettingsCalibration Set Levels on Line Input Channels Customize Setting for Your Particular Application SET UP the Phone InterfaceBuild Your Echo Canceller Reference Echo Canceller Reference for Multiple Vortex DevicesBus Reference Setting upAutomixer Parameters Configure the Automatic Microphone MixerGlobal Settings Channel Settings Automixer Settings for Multiple Vortex DevicesDefault Settings Configure the Matrix MixerBuilding Your System with Multiple Vortex Devices Assign Inputs Assign Outputs Configure the submatrixEF BUS Other EF2241 Features PresetsConfigure Your Echo Canceller Reference LCD Menu Tree LCD Menu StructureLCD Menu Structure System System MenuPhone Control Phone ControlInputs 1-4, T, A-D InputsAutomixer Menu OutputsGlobal Settings Mixer Settings Matrix Matrix MenuInput/Output EQ Channel Band Parametric EQ MenuMacros PresetsToo many microphones are gating TroubleshootingAutomatic Microphone Mixer No microphones are gating Some microphones are not gatingRoom Audio Sounds Choppy Echo Canceller ReferenceMatrix Mixer Residual EchoFinding the Source of Echo Room Gain Room Gain Excessive Room GainIn-Conference Quick Check Excessive Microphone Amplification Nonlinearity InsufficientEmail vortex@polycom.com Contacting Technical SupportTechnical Specifications USA and Canada ComplianceUS Telco requirements Canadian Telco Requirements Automatic Dialing Telco ConnectorRest of World AustraliaThis page was intentionally left blank CE Mark R& TTE Directive Vortex EF2241 Reference Manual Technical Support Noise and Reverberation Consider Room Gain Conference System DesignEN Echo Canceller, Noise Canceller EF2241 Block DiagramEF Bus Connector PinoutsInput/Output Remote Control Port Making AN EF BUS Terminator Connecting Unbalanced RCA to Balanced Mini PhoenixInstructions Additional Notes RMA# Must be on package Warranty InformationState Law Rights What this warranty does not coverCrosspoint Mix Minus Bus Echo CancellerDefinition of Terms Acoustic EchoNOM NOM Attenuation NOM Bus Presets Room GainDefinition of Terms Index NOM Index Page 1725-80098-001-C
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