Linking to a guy using an expensive ultrasonic mic to hear bats doesn't really support youe statement that you're hearing bats around you despite never seeing them. Maybe you have hearing damage?

Some species of bats spend more time in the upper ranges that no human can hear than others.

The spotted bat for instance, is found on west coast if North America and mostly calls at 11khz well within even older human hearing while other bats operate entirely outside human hearing.

Here is an alternative Piped link(s):

https://www.piped.video/watch?v=X4eqkaHkTAI

Piped is a privacy-respecting open-source alternative frontend to YouTube.

I'm open-source; check me out at GitHub.

Interesting. Probably the species around where I live don't make much noise, nobody else hears them here