I keep getting strange sound interruptions (for want of a better word) here and there.. reminds me of really old movies if you know what I mean

Here is a sample recording (just audio, there is no video)

You can clearly hear it at ~ 00:30+ seconds and there are other instances throughout the recording

I'm using freeswitch as a part of bigbluebutton project.

It's not that noticeable when your conversation is short however if you listen to a lecture it gets annoying.

I tried using different webcams, different PC\laptops, but it's all the same. It was tested with both energy level=100 and energy level=0

Could anyone help troubleshooting it?

What should I try changing?

Thank you