Or call me pedantic. Taminophile wants to show he can write about more than opera. Don't ask why.
Which of these sentence fragments is correct? (I'm not talking about content, but rather structural correctness.)
"Emma Matthews and conductor Richard Bonynge are beautiful musicians and...."
"Emma Matthews and the conductor, Richard Bonynge, are beautiful musicians and...."
Guess what? Both are!
However, one all too often sees this construction, which I quote directly from the source:
"Emma Matthews and conductor, Richard Bonynge are beautiful musicians and...."
Remember the four most common uses of a comma: to separate elements in a series; to separate two independent clauses, when accompanied by a conjunction; to attach words at the beginning or end of a sentence; and on both sides of a nonessential component.*
In the phrases conductor Richard Bonynge and the conductor, Richard Bonynge, "Richard Bonynge" is an appositive in both cases. Wikipedia defines an appostiive as "a grammatical construction in which two elements, normally noun phrases, are placed side by side, with one element serving to define or modify the other." The phrase conductor Richard Bonynge contains a restrictive appositive, because Richard Bonynge refers to the conductor about whom the writer is...er...writing. In fact, Richard Bonynge is one of the subjects of the sentence. Some other examples of restrictive appositives are My Friend Flicka, the idiot Baines(any "Waiting for God" fans out there?), and the tailor Motel Kamzoil. Restrictive appositives never require commas.
The phrase the conductor, Richard Bonynge, contains a non-restrictive appositive, because "Richard Bonynge" has the same function as a phrase in parentheses in the sentence above. The sentence functions the same and has basically the same meaning without it. Because of their parenthetical function, non-restrictive appositives always require commas. Before and after. Non-restrictive appositives are one type of nonessential component in the fourth common use of commas above.
There. I hope I don't have to tell you this again.
*This is not an exhaustive list. And you will note that in the sentence above, because one of the elements of the series had a comma within it, I used semicolons to achieve the same effect and avoid confusion.