People outside the singing world often wonder exactly how one goes about preparing an operatic role. Many think that it all happens in rehearsals, yet nothing could be further from the truth!
The preparation process may sometimes have begun YEARS before a role is even performed - most of us have "core repertoire" that we learn and work on even without any kind of offer in sight, the idea being to have them learned and ready to go in case somebody wants to hear them, or an oppportunity to "jump in" to a gig at the last minute emerges. A lot of time and energy goes into deciding repertoire both for auditions and "roles in preparation"; most singers have one list of "wishlist roles" (the roles they really want to sing and feel are best suited for their voices and temperament, usually the leads in operas from where their audition repertoire is drawn), and another comprised of roles they "should" know (usually easily-marketable repertoire that they know they could get called upon to sing at short notice, or in specific career-building situations, or supporting roles that might not be "first choice" roles, but which have a place in their repertoire). You can never really know too much repertoire - it's surprising how many singers have landed important contracts simply by being ready "just in case"!
When an offer comes in for a role which isn't yet in the repertoire, work begins immediately. Getting hold of the score (sometimes harder than it should be!), translating the text if need be, listening to as many recordings as possible to get some ideas of the overall "shape", various tempi and how others may have interpreted the music, and generally familiarizing oneself with the words, notes and rhythms. I personally like to read through the score at the piano a few times - I'm no great pianist, but I can paddle through it well enough in my own way, and becoming familiar with the orchestra part (even in a piano reduction) helps me learn the *music* rather than just my part.
After that, the real work begins: "singing it in". This is singer-speak for working through every single note and phrase largely for vocal and technical reasons, planning (and practicing) exactly how each note and vowel will be approached to get the best possible sound, building muscle memory and stamina along the way. This process has about as much to do with "making music" as a ballerina on a treadmill. It's physical coordination, nothing more or less. Sure, decisions as to vowel choices, breathing points and other details may be based on eventual musical/dramatic interpretation, but at this stage? It's about the mechanics of producing the actual sound. This is the longest phase for me at least - while I can do it quickly (I'm a quick study and have had to learn more than one role at lightning speed!), I'm happiest when I have several months so that I can do this work gradually and incrementally rather than trying to cram it all into a few intensely physical days or weeks; the longer time period gives the voice time to stretch and adapt to the particular physical demands of any role (singers always talk about their voices in the abstract, "the voice" - I've never quite understood why, but it's pretty standard parlance!). This is usually also the best time for me to work through the role with my teacher, who is wonderful at guiding those physical choices so that I can build the role into my voice the way I want from the beginning.
Because I have a good musical memory, I'm lucky in that the repetition of the singing in process usually also cements the text and music itself into my mind, so by the time I've done a fair bit of this technical work, I'm ready to coach the music.
In the classical voice world, "coaching" is not the same as a "voice lesson". While there is of course some crossover between them, the latter deals primarily with the kinds of mechanics described above - HOW the sound is produced. A coaching, on the other hand, is more about the music itself, exploring the expression, polishing the interpretation and musical shape. It's also great to work that music through with a pianist and get a feel for how ensemble changes things, even just with two - it's very easy to unintentionally "bend" the music to your own internal rhythms when you work it by yourself, but getting together with a pianist quickly points out where you may have been unintentionally cheating and have to get back to what's written!
Lastly, memorizing. Unlike straight theater where it's assumed you'll have the script in your hand when staging starts and complete the memorizing process as you rehearse, opera productions expect you to arrive off-book and ready to roll. Hopefully by the time one has done all the previous phases the role is largely in the memory already, but there are always places that need specific work, and this is the time to work those out. For me, the music is usually thoroughly in my brain, but words sometimes don't stick as well - I find writing it out longhand often helps with this, so you will often see me with a steno pad scribbling away....! Also, it can sometimes be helpful to work repetitions with a pianist simply to run through it for memory. While I'm a good study, credit where it's due: I'm blessed in having an "in-house" pianist, and my husband puts up with many hours of bashing through music I'm preparing with me as I get them sung-in and memorized. It's an incredible luxury, and one for which I'm profoundly grateful. The fact that he can sight-read just about anything makes it even better!
So, before the singer steps into the rehearsal room they're ready to start staging and shaping their interpretation with the Maestro and stage director. It's a collaborative process, of course, but an awful lot of the work happens alone, and a long time before the gig begins.