Just want to get an idea of what is normal with hearing if there is no environmental noise. I'm aware of tinitus, and curious if normally everyone has at least a mild case of tinnitus. Is your hearing pitch black when no noise is around?
At low enough environmental noise you might hear your own heart beating, especially when you have one ear against a pillow. I can hear that at around 4am in December or January when I'm staying up in the mountains for a weekend (when and where I don't need the A/C or fan but I'm still wearing socks). Then again, during that time of the year I'm very likely to have had steaks with a side dish of crispy, sauteed random pork bits (chopped face and ears, belly strips, liver, with onions and chili peppers) and lots of beer, plus a few cigars, so my heart's beating a lot harder (walking up a mountain slope, even on a paved street, is still tiring when it's a 65deg incline, even if it's cold and I don't sweat).