Dynamic Range Compression (DRC)

Dynamic Range Compression (DRC) is a feature in the Zenitel IP devices. The DRC function is processing the audio signal, and helps even out the loud and quiet parts. Lower signals will get gain applied, but not more than there is headroom for up to digital full scale.

For intercom devices and IP Speakers the DRC will normally have a good effect on regular speech signals, and will often increase the loudspeaker output noticeably. For already maximized signals, such as prerecorded alarm tones, DRC will have little or no effect.

The DRC function is by default disabled. The DRC is a dynamic digital signal gain adjustment function, and some signal clipping may occur if the DRC is configured to use high gain. The DRC function works very well in combination with the Automatic Volume Control (AVC).

Configuring the DRC feature

Configuration is done from the Audio Settings menu. First enable Advanced Configuration mode. Depending on the mode of operations, select:

• Edge mode: Edge Configuration > Audio Settings > Audio signal processing
• SIP mode: SIP Configuration > Audio Settings > Audio signal processing
• ICX-AlphaCom mode: Advanced ICX-AlphaCom > Audio Settings > Audio signal processing

Dynamic Range Compression configuration menu (firmware 7 and later)

• Enable AEC: Check the box to enable suppression of echo on the microphone signal. Default enabled. If disabled the loudspeaker and microphone will be open without any audio processing.
• AEC mode: Sets the aggressiveness of the echo suppressor. A higher level trades off double-talk performance for increased echo suppression. Available suppression levels:
  • Low
  • Moderate
  • High
  • Half Duplex

With "Half Duplex" the loudspeaker will be muted when speaking into the microphone.

High or Half Duplex can be used in noisy or acoustic challenging environments, or in customized stations without optimal acoustic design, where one is experiencing issues with echo, chopping audio or one-way audio.

For devices operating in Open Duplex the AEC needs to be enabled. If the AEC is disabled and the device is used for two-way loud-speaking communication, it is very likely to get acoustic feedback (aka Larsen effect) All audio settings can be reset to default values by selecting Factory Reset Audio Settings.