Indeed, if a person I know I will be talking to a lot notices I usually tell them. People don't care - in the good sense. It's usually talking to strangers that may cause issues. While as a child it was store clerks who I had an issue with, as an adult it's tense moments where you have to protect your interests, explain something complex to strangers, point the way to a tourist, etc. - stress-free vocalization would really help out in those situations
