Why does Hedda sit down to play "a frenzied dance melody on the piano" as a prelude to committing suicide?

 Hedda's frenzied act of  playing the piano is an outward manifestation of her inner frustration and fury, which culminates in her own 'beautiful death'. Even as early as act one, when Tesman leaves the room, Hedda goes to the window and whirls about 'in a frenzy', which symbolises her claustrophobia and despair at the knowledge she is pregnant. The title of the play, 'Hedda Gabler' is very telliing. Throughout the action, Hedda tries to sustain her role as General Gabler's daughter, rather than Tesman's wife. However, she is only prepared to play this role within the confines of her drawing room. She married Tesman because she had 'danced herself tired' She loves Eiljert but rather than leave Tesman, she prefers  Lovborg to die beautifully 'with vine leaves in his hair'. When Brack reveals the sordid reality of Lovborg's death, Hedda's is distraught and can only express her grief through the wild melody she plays on the piano. This is her last act of rebellion, an expression of individuality and an ironic victory over the social forces which dictate she should  behave as a late nineteenth century woman, passive, demure and docile.