The trouble is that half the conversation is missing, involuntarily increasing the attention of bystanders. Lauren Emberson called that 'halfalog'. https://journals.sagepub.com/doi/abs/10.1177/095679761038212...

Some people just want to commute in silence without listening to overly loud work-related calls made by other people.

I’m one of those people, myself. But then I remember that public transportation means that there might be other people around, and we’re not at a concert where people are not allowed to talk, and that I can’t always get what I want, to paraphrase the Rolling Stones.