DS-2CD2425FWD-IW - noise (screeching) when using camera speaker

[Neverwhere]

The speaker on my DS-2CD2425FWD-IW camera produces a screeching noise when I turn on the microphone symbol on the iVMS-4500 app on the iPad (to try to speak through the camera).
The noise occurs whether the camera microphone is set to on or off on iVMS-4500 (i.e., speaker symbol on iVMS-4500 set to on or off).
The noise also occurs whether using local or external network.
So makes speaking through the camera unusable.

Listening from the camera over the iVMS-4500 app works fine.

Summary:
Audio from camera to iVMS-4500 is fine when listening on iPad.
Audio from ivms-4500 to camera is garbled noise when listening at camera.

Hikvision support could not help.
Latest firmware is installed.
I have 2 of these cameras. Both have this issue.

How do I fix this?
Please let me know.

Thank you.

 

[K175un3]

Hello Neverwhere, could it be a feedback loop?

 

[Neverwhere]

Hello Neverwhere, could it be a feedback loop?

What is that/how would I detect this?

 

[K175un3]

What I'm thinking is that the microphone and speaker are interacting, causing a feedback loop.

As when you're not using the speaker on the cam Neverwhere, you don't get the issue.

It may well be worth finding a good audio forum, as I only have a 101 understanding.