Look ... I'm in theatre, and I know from personal experience and from witnessing others that with a great vocal coach, one can gain a full octave in no time. Singing is actually really easy; you just have to have the motivation and passion; that's the only God-given gift the greatest singers have, and they exhibit it every time they perform.

I'm not gonna lecture y'all on speech level singing or any other method, unless you want me to. The common mis-conception is that singing really well is dificult. It's not, and all of the great vocal coaches and vocalists will tell you that. Even somebody with a heavy studder in their speaking voice can become a great singer; in fact, that's a technique that some therapists use with their patients. People who have damaged their throats with cigarettes and/or drugs, with the right training, can practically reverse the negative effects on their singing voice.

The vocal chords are amazing; they're a couple of extremely tiny muscles (imagine latex) that have this magnificent ability to expand and grow. A great coach will tell you that nobody is limited; that there is no difference between the vocal abilities of a wonderful singer and those of one that is not so good. And it's true.

I'd rather have Ozzy take lessons to strengthen his throat and chords, as opposed to ditching songs (due to an extremely limited range now) and someday in the near future abruptly end his touring career.

Ozzy would still sound the same; his singing voice'd just be a hell of a lot stronger. He'd also get lots of vocal advice from the coach, such as not to sing when you're really sick.

But, a "good" vocal coach ... there are plenty of bad ones out there, and people out just to make a buck and "nothing" else.