I don't know how fidele this recording is, phone -> email -> MP3
player ->DSO , timings off the DSO cursor. I make that a principal repeat (A-B easier timing than on the
ill-defined complex curve of same repeat) of 103 Hz and next most observable repeat (B-C)
of 475 Hz.
So is it mains initiated ?
103<>100 , I will assume that is twice mains frequency as principal
component
