Has anyone tried Oto App for Tinnitus?

My father has severe tinnitus, which originally came from Chemotherapy in his younger days. Hes 74 now, and it has become debilitating for him. I have recently read that the trials of Oto-313 were unsuccessful.

I have come upon the Oto App, which is not a cure, but says it helps manage tinnitus on a daily basis. I don't trust app reviews, because they can be so easily manipulated, but it does have a lot of positive ones.

To me it just seems like, what can they really do from an app, that one wouldn't already have tried when suffering from tinnitus for so long?

Does anyone have any experience with the Oto App? Would you recommend it? Why, or why not?

Thanks!