I purchased this noise reduction plug-in for a test.
It seems extremely good, watching this video... but...
It doesn't suit to my video... maybe. *please see the PS below
I checked the original sound, the sound after reducing the noise on Audacity and Brusfri and found out the sound created with Audacity remained subtle sounds even after reducing the noise. Brusfry removes all the sounds including the subtle sounds that I want to keep.
This doesn't mean Brusfry isn't good at all but it is just my video's sound doesn't have strong difference between the noise (mostly hiss sound) and the subtle massage sounds. Audacity is a free app but it does a really good job to reduce the noise and remain sounds that I want to keep...
With that being said, reducing all the noise completely can lead to have unnatural feelings. But personally once I watch this noise-less videos and go back to the old videos with hissing noise, it sounds a little annoying, too.
Well, I have to find a good solution to make the sounds more natural and easier to listen to.
Later I figured out that if you edit with Brusfri after recording with Zoom H6, it reduces not only the noise but also the hand movement sounds which I want to keep.
It is better to edit the sound which is recorded directly from the camera CS-10EM is plugged in.