Built-In Audio Processing Features; Automatic Gain Control; Background Noise Suppression; Comfort Noise Fill - Polycom CX5500 Administrator's Manual

Polycom CX5500 Unified Conference Station Administrator's Guide
1.1.0

Built-In Audio Processing Features

Your CX5500 system has the following built-in audio processing features: automatic gain control,
background noise suppression, comfort noise fill, dynamic noise reduction, jitter buffer and packet error
concealment, and low delay audio packet transmission. These features work automatically, without
configuration changes.

Automatic Gain Control

Automatic Gain Control (AGC) is applicable to handsfree operation and is used to boost the transmit gain
of the local talker in certain circumstances. This increases the effective user-phone radius and helps with
the intelligibility of soft-talkers.

Background Noise Suppression

Background noise suppression (BNS) is designed primarily for handsfree operation and reduces
background noise to enhance communication in noisy environments.

Comfort Noise Fill

Comfort noise fill is designed to help provide a consistent noise level to the remote user of a handsfree
call. Fluctuations in perceived background noise levels are an undesirable side effect of the non-linear
component of most AEC systems. This feature uses noise synthesis techniques to smooth out the noise
level in the direction toward the remote user, providing a more natural call experience.

Dynamic Noise Reduction

Dynamic noise reduction (DNR) provides maximum microphone sensitivity, while automatically reducing
background noise— from fans, projectors, heating and air conditioning—for clearer sound and more
efficient conferencing.

Jitter Buffer and Packet Error Concealment

The phone employs a high-performance jitter buffer and packet error concealment system designed to
mitigate packet inter-arrival jitter and out-of-order, or lost or delayed (by the network) packets. The jitter
buffer is adaptive and configurable for different network environments. When packets are lost, a
concealment algorithm minimizes the resulting negative audio consequences.

Low-Delay Audio Packet Transmission

The phone is designed to minimize latency for audio packet transmission.
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