Why is it rude to mumble under your breath?

Mumbling under your breath can be perceived as rude because it often excludes others from the conversation, leaving them feeling disrespected or dismissed. It can create an atmosphere of secrecy or negativity, suggesting that the speaker is unwilling to communicate openly. Additionally, it may lead to misunderstandings, as those nearby might misinterpret the mumbling as criticism or contempt. Overall, clear communication fosters respect and understanding in social interactions.