Why does ernie's piano playing make holden feel even louiser than before?

In J.D. Salinger's "The Catcher in the Rye," Holden Caulfield feels increasingly lonely while listening to Ernie play piano because Ernie's talent highlights Holden's sense of alienation and disconnection from the world. The beauty of the music contrasts sharply with Holden's emotional turmoil and feelings of inadequacy, intensifying his loneliness. Instead of bringing him joy, the performance serves as a reminder of the connections he lacks and the isolation he experiences in his life. This moment deepens Holden's introspection and despair, making him feel even more isolated.