Was present for about 2 months but has now completely disappeared. Probable cause was noise induced. Started as a high pitch whistle and then a hissing. Occasional H. Started to fade at about 6 weeks and now has completely gone. Didn't do anything specific to help (wish i could help everyone here and say i did x,y,z but i just got better). thought about signing up for AM101 but didn't proceed as it had disappeared. Hopefully it won't reoccur. This is an amazingly supporting forum and I wish you all the best. On to new health problems now!