Potential!
I think this app has the potential to be very useful. Some things that would make it better:
Easier cropping. I found myself battling with its sensitivity when I tried shortening the length of it.
Crop size. I found it to be a little too large. The white noise in my video was isolated from other noises for only a brief moment and because the crop size was too large I was not able to select just the white noise, making the app unsuccessful for me.
I think with these little improvements the app would become more versatile and useful to more people!
Goolpong about
Denoise - audio noise removal