Question

Why did everyone whisper in the hall at number 12 grimmauld place?

Answer 1

Everyone didn't want to wake up Mrs. Black and her shrieking. Everytime someone wakes her up she yells and tells everyone to leave since she dislikes the order of the Phoenix members entering into her house but they have to stay there and endure her screaming since it's the safest place to keep hiding Harry from the death eaters and Voldemort.