Why does Sal say she sounds like Phoebe when she says "I don't want to hear it"?

Sal sees Phoebe as a parallel version of herself. Both have had their mothers leave them, and Sal initially reacted to this in the same way that Phoebe does. Both girls rationalize the desertions, blaming it on some other circumstance and avoiding the knowledge that both Mrs. Hiddle and Mrs. Winterbottom chose to leave. Sal and Phoebe try to convince themselves that their mothers would never leave children that they loved. Yet in fact they did. Sal is beginning to realize this as she watches Phoebe. She tries to speak some truth to Phoebe, but Phoebe does not want to hear it, just as Sal did not want to hear her father discuss her mother’s departure and Margaret Cadaver’s role in her father’s life. While Sal has not fully accepted the truth of her situation, she is a few steps ahead of Phoebe; Phoebe tries to convince herself that her mother was kidnapped instead of leaving of her own choice. Phoebe has become Sal’s mirror of her own voice, her own thoughts, and her own behavior. This gives Sal some perspective to deal with her loss.