Answer to Question 1
In Psycho, the main character (Janet Leigh) drives her car through a
rainstorm. On the soundtrack, we hear her windshield wiper blades slashing
furiously against the downpour. Later, when she is taking a shower in a motel, these
same sounds are repeated. The source of the water noise is apparent, but the slashing
sounds seem to come from nowhereuntil a demented killer crashes into the
bathroom brandishing a knife.
Answer to Question 2
Realistic musicals are generally backstage stories, in which the production
numbers are presented as dramatically plausible. An example would be A Star Is
Born. Formalist musicals make no pretense at realism. Characters burst out in song
and dance in the middle of a scene without easing into the number with a plausible
pretext. An example would be Meet Me in St. Louis.