Originally Posted by MarioD
Another suggestion would be to upload the song to let others listen and try to determine the cause of said sound. You could load it to the free Dropbox and post its URL.

I haven't followed this thread closely so if this has already been suggested then I apologize for the redundancy.
Yep, the files have been uploaded and evaluated. Some are available at this post:
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Number=840649#Post840649

The majority of listeners agree that the sound is the natural sound of the performing artist playing brush swirls on the snare. The O/P refers to the noise as a 'hiss', so I'm not sure if they are familiar with snare drums and brush techniques.

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