My low frequency hearing is good, but the high frequencies are really bad. 24 years of exposure to fighter jets does that to your hearing they tell me. No kidding !. Both ears are very similar but when above 2000 hz it drops pretty fast to 60dB. Maybe that explains it, but I would have sworn the noise was caused by high frequencies. My Audi did turn down the gain at 3 of the higher frequencies because I noticed it when reading in a quiet area.