The soft vibrating that you feel in your bones, it's nothing more than the humming air, handsaws twanging, cats purring too many to hear.
Madness string 37761
And yet it still happens frequently enough that I have to put it in our shop's initial safety briefing. If they're running a machine, don't even fucking talk to them, stand off to the side and wait until they're done. Anyone who breaks this rule then has to watch lathe accident videos for a better understanding of why the rule exists.