A little quieter than my old Logitec gaming keyboard. But it sounds good and crisp. I don't think you can adjust/muffle the sound.

Thanks for your great answers, I have ordered them :)

I think the keyboard is really great. But I wouldn't have thought that the keys are "so loud". Nevertheless, I would buy them again!

very loud, but somehow a cool sound. i don't know if there is a quiet version of it.