In Piano what cause the speaker to recall a memory?

In the poem "Piano" by D.H. Lawrence, the speaker recalls a memory triggered by the sound of a woman singing and playing the piano. The music evokes feelings of nostalgia and longing for his childhood, bringing back vivid memories of his mother and the comfort of being in her presence. The emotional power of the music acts as a catalyst, allowing the speaker to reconnect with his past and the innocence of youth.