The polka music, the Varsouviana, is one of the most important of the play’s many symbols. It represents Blanche’s worsening state of mind in the play.
We learn from Scene Six, when Blanche relates the tragic story of her young husband’s death to Mitch, the special significance that this polka tune has for her. It was the music playing at the dance when her husband, Alan, shot himself in despair after Blanche had discovered that he had an older, male lover. Therefore, this music serves as a constant reminder of that terrible event, which set Blanche on an ever-increasing downward spiral from then on. It also symbolises the vestiges of the one true romance that she ever knew in her life – we learn from her sister Stella that she was simply infatuated with Alan. However, for Blanche, the memory of romance is inextricably mixed with sadness.
The polka music recurs with increasing frequency throughout the play. By the end of the play, it is playing constantly in Blanche’s head. As she says to the uncomprehending Mitch:
Have you ever had anything caught in your head? Some words, a piece of music? That goes relentlessly on and on in your head? No, of course you haven’t, you dumb angel puss, you’d never get anything awful caught in your head! (scene 9)
Blanche has the ‘awful’ polka music caught in her head, showing how she is continually prey to her memories of Alan. In short, this music torments her. We can note that, as she relates Alan's suicide to Mitch, it plays in an ominous minor key.
However, the polka music serves not just as a reminder of the past, it also foreshadows the future, which for Blanche is equally grim as the past, as by the end of the play she is committed to a mental home. When the authorities come to take her away, the polka music re-appears in a terrible, ‘distorted’ form, mixed with ‘inhuman cries’ of the jungle, symbolizing that Blanche’s nervous breakdown is complete by this point. It also appears when Stanley callously gives her a going-away ticket for her birthday. At this moment it plays 'softly' but it still signals a moment of great mental distress for Blanche.
The polka music, then, has some very unsettling associations for Blanche; it represents her mental suffering and turmoil. It appears in various, contradictory guises, sometimes soft, sometimes insanely distorted, and in major and minor keys, but it always torments Blanche. In essence, it symbolizes both her bleak past and equally bleak future.