Which are the revelations/epiphanies that occur in the living room and in the nightclub?Please explain what the revelations are, and how they...

The narrator of "Sonny's Blues" by James Baldwin finally talks with the brother from whom he has been alienated.  Years ago Sonny would come by his house, but the narrator perceived him as "loose and dreamlike all the time" and he disliked his friends.  But, now as adults, the narrator realizes that he should listen to Sonny, for Sonny is "doing his best to talk."  And, as Sonny speaks of his addiction to heroin, his attempt to keep from suffering, the narrator realizes that there stood

the fact that I had held silence...when he had needed human speech to help him.

The narrator's epiphany in the living room is that beyond the "power of time and forgiveness" is the power of listening, a power that could have helped Sonny.

Later, at the nightclub, the narrator listens as Sonny plays the blues and jazz.  He enters Sonny's world, his "kingdom.  Here, it was not even a question that his veins bore royal blood."  The narrator now respects his brother Sonny, perceiving what a great artist he is.  He confronts another moral truth:

...the man who creates the music is hearing something else, is dealing with the roar rising from the void and imposing order on it as it hits the air.  What is evoked in him, then, is of another order, more terrible because it has no words, and triumphant, too, for that same reason.  And his triumph, when he triumphs, is ours.

The narrator does experience two epiphanies.  However, they both come from his realization that he must listen to his talented brother who needs his ear in both situations.  "Meaning depends upon sharing," writes Joseph Conrad in a short story.  Certainly, meaning for both Sonny and his brother greatly depends upon their sharing of their inmost souls with one another, for then they can understand each another.