I live near a deep sea port. 24/7/365 there is the sound of ship generators running, which creates a very deep hertz discordant sound/vibration that drives me nuts. Earplugs do not work as it is as much vibration as sound. My “fix” is a base heavy bluetooth speaker that I stream a low hertz 12 hour soundclip that has a low, but even tone rumble. It masks enough of the port vibrations (which are not even, but annoyingly random) that I can often get to sleep. Might work for people trying to mask other deep hertz sounds that earplugs do not help with, e.g. music base, low hertz industrial sounds etc. I hope this is helpful.