Yeah I've seen this. There's no need. A needle is fast and easy. Hurts a little but who cares? You can't be a wimp and have tinnitus. Besides, you'd have to mix, therefore diluting, any drug, with ferrous (metals that interact with a magnetic field) nano particle and hope that it isn't ototoxic. Do you want ferrous nano particles floating around in your cochlea? I'll answer that for you. "Hell no".
I really don't see this being feasible in any way. It's a dream.
The best way is to use IT injections and then just lay there with your head tilted for an hour or so while the substance diffuses into the round window.
Also concerning Otomagnetics, think about it. The middle ear is a hollow cavity. You won't be able to use this technology to introduce a large enough amount of substance quickly enough to fill up the middle ear to the point were it is resting on the round window, it will only diffuse through the eardrum very very slowly. It would take hours and hours to permeate the eardrum with the same amount of substance that you could just inject in 5 seconds. Also, how can the magnet be on the same side as your head as the ear your treating? Magnets attract. You would have to position the magnet on the opposite side of the head as the ear that you are treating. A forward facing magnet cannot suspend ferrous material at a set distance, that's called levitation and can only be achieved with materials that are supercooled cryogenically.
Like I said, this is a dream. There's nothing wrong with an IT injection with a needle, so long as the physician is competent.