My dad has this habit of making the ‘hawking phlegm’ sound when he bathes, and that means every single day. He does not have any coughing problems, and does not smoke. It is extremely irritating, and I have brought this issue up to him, but he always tells me to accept it, and refuses to change. My mom has no issues with his habit, and also accuses me of being unreasonable. I am at a loss over what to do now. Any advice?