This study shows they are still investigating tDCS. 175 subjects. No placebo control group. Assessment of sound level reduction and annoyance by the patient on a EVA. They think polarity and placement of electrodes gives specific results according to the laterality of the tinnitus: If your tinnitus is unilateral it is more likely to work but they have to work out how to place the electrodes according to the side of your tinnitus. Or i read too fast. Few responders. Chapter 3 is very interesting.
http://www.hindawi.com/journals/np/2014/930860/
http://www.hindawi.com/journals/np/2014/930860/