According to the book “The Unknown Callas”, Maria Callas presented with a wobble as early as a teenager.

This is no doubt due to the fact that Maria Callas sang TOO LOUDLY during these formative years of her training.  She was not only singing too loudly, but was encouraged to do so by her teachers, Maria Trivella and Elvira de Hidalgo.

Based on her training with de Hidalgo, one might think that Callas had a good teacher.  However, after considering the fact that de Hidalgo arranged a contract for Callas at the National Opera when she was just seventeen, it becomes clear that her teaching principles aren’t above reproach.  Callas had only been studying with de Hidalgo for six months.  Voices are not built in six months.

It’s also rather interesting that both de Hidalgo and Callas’s careers ended when both women were in their early 40s.

When there is a lack of a balanced training in any functional part of the voice (high/low, loud/soft, fast/slow) tonal unsteadiness and constriction will be the natural result.  When the arytenoid (AT) system is too vigorously used (as in loud singing) without a commensurate balance (as in softer singing), the voice will struggle to find an equilibrium.

It’s important to note that a wobble is more FUNCTIONALLY free than a tremolo or ‘bleat’.

A rather telling description of Callas’s tendency to ‘over-do’ is mentioned by her colleague Zoe Vlachopoulou:

“On the bus journey to the seaside in 1939 Mary sat next to Zoe Vlachopoulou, who on 23 June had obtained her diploma with distinction after only two years with de Hidalgo.  They talked about music and singing, as Mary could never be drawn into discussing personal or family matters.

…All Mary talked about was opera: the requirements of this or that role, the problems of staging and acting, the way a good leading man could draw out the best in his partner.  But one subject she never discussed was the wobble in her voice, and even de Hidalgo took care not to use the word when giving her exercises designed to eliminate the problem. “At the National Conservatory with Trivella, she had strained her voice by singing unsuitable pieces,” says Vlachopoulou, “and this created problems for her when singing forte, especially at the top of her register.  After only a few lessons with de Hidalgo, however, the wobble began to go away.”  

On that outing in 1939 Mary and Zoe went off and sat on a rock a little way away from the others, talking about this and that. “After a while,” Vlachopoulou recalls, “I started singing ‘Una voce poco fa,’ pianissimo at first.  As we were by ourselves on the rock, looking out across the open sea, she joined in and sang the whole aria with me. ‘Hey!’ I said to her at the end, ‘you’re so good at the vocalises and you’ve got such lovely pianissimo! Why don’t you ever sing at less than your full volume? I didn’t say anything about her wobble, but that was all I was thinking of, of course.  She didn’t know how to answer, because all that volume and power came naturally.  But the fact is that Maria sang much too loud in the early days: her voice was a tremendous raw mass!”

Petsalēs-Diomēdēs, Nikolaos Athanasiu.“The” Unknown Callas: The Greek Years. Hal Leonard Corporation, 2001.