Why microphone access ?

[bgroper]

Hi forum
Newbie here.
I've been testing the IP Cam Viewer Lite, and becoming annoyed by all the ads.
So I'm trying to upgrade to Pro version.
Understand that the viewer needs to access the photos and media files in my phone.
Why does IP Cam Viewer Pro need access to my microphone ?
That seems spooky.
TIA's

[N4Spd]

https://hit-mob.com/ip-cam-viewer-android/faq/#14

2-way audio.