system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: what is that random high pitch ringing in your ears and why does it happen?
gpt
There are two forms of this.

One is called tinnitus and is an injury caused by loud noise exposure. The other posters covered this one. It's most common from using loud things (firearms, power tools, etc) with no hearing protection. It can also be easily caused by headphones or earbuds if you play music loudly, because they are so close to the ear they can do damage over time even if you think the volume level is comfortable. When using headphones you should always use the lowest volume that lets you hear clearly.

The other one is called "pulsatile tinnitus" and is caused by the blood rushing through your ears. It's literally always there (unless your heart stops - not good) but it's not very loud and you almost never notice it. When things are quiet enough, and you are very relaxed, you may start hearing it as a pulsing "whoosh" or as a high pitch ring that fades in and out. This is actually hearing your own pulse and is completely harmless. It should never be loud enough to stop you from hearing other things, if that is happening you probably have regular tinnitus.