Callas Vs Tebaldi (Suicidio Live 1974)

Here is a comparison side by side of Callas and Tebaldi 1974 comparison of the aria Suicidio from La Gioconda! I really wonder and try to explain how is it possible the Destroyed Voice a shadow of herself Callas to sound so so much better than the Famous Tebaldi who in 1974 was still receiving great critics for her singing!! I will do with the Cavalleria aria later…but to my ears is impossible to talk for Callas saying that her voice is destroyed by 1974 and say that Tebaldi still sang good!