I always admired the purity of her voice — it sounds like water. Perfect technique joins here with emotional pathos. We hear it especially when she says “mezzanotte”– after which singing becomes not just singing, but a kind of mixture between singing and scream of terror at seeing the horror of the cemetery. And in the last prayer, “miserere, m’aita o Signor” we hear desperation and are moved by an amazing piani which became a signature of one of greatest sopranos in the history.