It's probably that you are now aware of your own personal frequency.
It's part of waking up spiritually, apparently. You might want to start meditating -it can be very helpful.
Pay attention to your thoughts if the tone get louder. Does it get louder with loving thoughts or not? It's different for everyone it seems, there is no right or wrong. It just is.
There is no reason to fear it. Usually one ear buzzes constantly with the other ear only occasionally. Think of it as trying to get your attention – You'll have to figure out what that is by watching your thoughts.
Not everyone will have the constant ringing. Pay no attention to anyone who claims they are superior because they rarely hear it.
I forgot one thing that is very important. We all have inner guidance. Religions ignore this and replace it with false idols.