So having recently had to drive a diesel truck around for a few months, I noticed that they are fucking loud. If you’re outside of a diesel while it’s running, it is definitely worth wearing ear pro. Suggestion: being near a running diesel engine Impairs Hearing.
Along with that. being able to hear movement underground while driving any sort of vehicle seems impossible, but when I drive through those areas with the Irradiated Wanderers (in a diesel, no less), I get swarmed with little yellows Vs.
Suggestion: make MOST noises on different Z-levels harder to hear (need Accute Hearing or whatever to pick them up, generally).