A stranger may feel uncomfortable if you have a cell phone conversation while standing 18 inches or closer to him or her, especially if the conversation is loud, long, or highly personal. this is because

Actually this is because its human tendency or habit, that humans get disturbed or tensed when a person talks loudly very near to him or her, hence here the stranger would have felt uncomfortable for the irritation caused by the loud cell phone conversation by a unknow person close to the stranger, then it’s a human psychology to get distracted in these type of cases for sure.