Ultra low frequencies are my problem. When it is quiet (at night), if there is anything generating low frequency waves anywhere around, I may hear it. It feel

Ultra low frequencies are my problem. When it is quiet (at night), if there is anything generating low frequency waves anywhere around, I may hear it. It feels like an incredibly subtle repeating gentle puff of air entering the ear (which makes sense, given that it's a pressure wave). And unfortunately, one ear is more sensitive to it than the other, which gives me a feeling of uneven pressure from one side of my head to the other. There is no cure for this, as far as I know, because it is an external sound. And it's nearly impossible to identify the source for many reasons (difficulty in detecting/recording, ease of transmission through solid objects (such as the ground), and long waves which can carry very far). It just takes a little ambient noise to mask it. The sound isn't painful, per se, because it's very low amplitude. But when there is nothing else to distract, it feels like having your head inside a washing machine. Sources can include large engines (locomotive, truck, ship, whatever.), heavy equipment (particularly at factories), and my favorite - wind over a mountain ridge. The last one can carry for miles!