53:21 for hissing, an 10 cicadas.
From this point of view it is in most cases complete nonsense to determine a tinnitus frequency. Because in most cases tinnitus has no frequency at all, just as white noise has no frequency.
Do cicadas have a frequency?
Nevertheless, tinnitus experts try to determine a tinnitus frequency, and they look surprised and sceptical when you report that your tinnitus is a hiss and a cicada and not a beep.....