Different audio support depending on the Avonic camera model:

CM22

This camera has a built-in dual noise-cancelling microphones with 4-meter pickup range (Audio from the microphones is embedded on the USB output, not on the HDMI output. There isn't any connector to embed external audio)

CM41

This camera does not have any option to embed audio 

CM44

This camera does not have any option to embed audio 

CM40 (CM40-IP) 

This camera has a 3.5mm jack audio Line in to embed audio on HDMI and SDI (not on USB output). It supports line-level audio, it has no pre-amp for microphones built-in.

(In the camera web GUI as by HTTP API Audio, it is possible to enable or disable the audio, to configure the sample rate, bitrate, audio delay, input volume, etc)

CM7x-IP

This camera has a balanced audio Line in 5-pin phoenix connector input to embed audio into the IP stream, SDI and HDMI outputs (not on USB output) 

(In the camera web GUI as by HTTP API Audio, it is possible to enable or disable the audio, to configure the sample rate, bitrate, audio delay, input volume, etc)

* See Balanced Audio Connection in CM7x