Discuss with him in a friendly way, see if it is the hobby of the elderly or the practice of the children, and tell them your rest time. Generally speaking, if it is the hobby of the elderly, they will understand, just stagger the time. If it's a child, it's a little troublesome. Try to ask him not to practice the piano during your night off. In addition, you can suggest that they change to a better teacher. Generally, children are very sad to play erhu because the teacher's level is limited. Haha, I wish you a happy mood! _ I am the erhu teacher:-D.