Hi we are using a GV800 card and GV software

Hi we are using a GV800 card and GV software version 8.3 Recently we have replaced the exisitng cameras and also connection wirings. Now we are able to see the video but we are unable to hear any sound. When we check this under audio setup a very loud noise sound is received instead of actual voice. The cameras we use have a direct port for power supply, one seperate port for video and one seperate port for audio.
it seems there is ome problem with the wires/sockets. Please advice how can we correct the wiring