I've noticed this bug atleast since the industrial DLC. Playing career mode, after doing a few missions, the handheld welder and fire extinguishers no longer make any sound when used by ME. However, as seen in the video posted,

https://www.youtube.com/watch?v=WhgbQW8sv9I

my friend does not have this issue. I can hear HIS handtools, and he can hear his - but neither of us can hear MY handtools. It's as though the tools themselves just are not emitting audio, when wielded by my player. Starting a new save will solve the issue for a bit, until it comes back again. Verifying game files does not solve anything.