I've been told that shooting caused mine, but I've been careful to wear ear protection, so I don't buy that explanation. I grew up on a cattle farm. Routinely cutting, raking & baling hay. I always would sit almost sideway on the tractor, watching the cutter or baler, etc. My left ear was always turned toward the engine and today my tinnitus (and hearing loss) is much worse in my left ear. Combine that with years of driving with the window rolled down. I think this is why my left ear is worse. While mine is very VERY loud, all the time, its worse when I'm stressed, angry, worried or when I have a sinus congestion.