The following steps will walk you through how to enable audio so you can hear/record it through the SIBELL NVR. Please remember this is an EL camera being paired with a SB NVR so you will need to access the camera directly in order to configure this properly.
IPVD-EL4IR28A & IPVD-EL2IR28A
These steps will also apply to other SIBELL NVR's...
Step 1) Access the IP camera web interface directly, and navigate to Camera > Audio.
Step 2) Make sure Main Stream and Sub Stream are both enabled and both have the same settings as the image attached, then save.
If you do not make these settings identical to mine it, the audio will be delayed and sound like Frankenstein is coming through the MIC.
Step 3) Log into your NVR and add the camera.
Step 4) Go into the encode settings of the NVR and make sure audio is set for "ON" for the channel this camera is added to.
Step 5) Simply go to the live view and open the audio by clicking the speaker icon, and enjoy.