How loud (decibel) is a mouse click?

Without static noise attenuate feature turn on, its can be quite loud enough to be bothered with.

55-60dB is pretty noticeable in quiet room with only fan/computer noise in background.

But in normal situation, talking everywhere in the office or room. You should not notice it.

Normal noise these days @ 70dB is pretty normal. Below that, its not annoying… much