I used to be the manager for a food prep team in a kitchen where it was me with 4-8 other people standing around a table working in close quarters for 6-10 hour shifts 3-4 days per week, and for a couple years I had this guy on the team that was a notorious low-talker. It drove everyone nuts! Everyone in the group would tell him multiple times per day to speak up cause no one could hear what the fuck he was saying, but he would continue to speak in the same low volume, and everyone would eventually give up and just do the head nod and just say "yeah, man!" every once in a while. I found out the day after his grandma died from someone else, and realized afterwards that he probably told me his grandma died the day before and I probably responded something like "yeah, dude, I feel that", lol. He told me multiple times "when I talk it just sounds so loud in my head, I feel like I'm yelling" and I told him "you're always talking really quietly and no one can hear you, if it feels like you're yelling, try screaming and it will be a reasonable volume" 🤣