I haven’t had it for that long but I have had it for around twenty years. Like yours, mine sometimes stops and sometimes it is much louder than at other times. Mine sounds like insects of some sort and the last time it went away for any length of time was in 2009 when I went with a family group and rented a beach house and went swimming in the surf every day for a week. After four or five days of spending an hour or more a day in the surf my tinnitus was almost unnoticeable but it came back within a week of returning home. Maybe I should soak my head in salt water every day.