how do biff and happy react to their fathers beginning to talk to himself more and more loudly and noticably? about what were they concerned

Biff and Happy come downstairs in their pajamas, and ask Linda how long Willy has been talking to himself. Linda says that this has been going on for years. Linda says that she would have told Biff, if he had an address where he could be reached. She also says that Willy is at his worst when Biff comes home, and asks Biff why they are so hateful to one another. Biff claims that he is trying to change. Linda attributes her husband's hallucinations to Biff's presence, likely a sign that Biff reminds Willy of his failures as a father and as a businessman. Happy just feels dad and guilty for not being able to help his father.