I am not a music guy. When I was in the fifth grade play, the music teacher asked me if maybe I could sing a little quieter. In eighth grade, I was directed to speak the lines to my song while the cast danced behind me. I played Bernardo in West Side Story my senior year of high school, and they gave my solos to one of the other Sharks. I don't know if I'm tone-deaf or what, but I've never been able to understand what's really going on with music.
So I have a bit of a mental block about it. I listen to music all the time — indie rock, some electronica, a little hip-hop. But I have no background in classical music, and finding the right music for a play set in the past is always a big challenge.
My usual technique is to look up what composers were popular in the period, and then search the web for samples. I've heard it said that strings work best as score for live theatre, as opposed to a full orchestra — and that matches with my experience. So I often end up on Amazon, listening to the 30-second samples of a CD from a string quartet performing music from the period of the play.
Since Art Nouveau is already an influence on the design of the show, I tried to determine whether there was a musical side to the Art Nouveau movement. This didn't lead me very far — either there wasn't much of a corresponding musical movement, or I couldn't track it down. But Lucas advised me to check out Erik Satie, and that name came up in my research on the period as well. An Amazon search for Satie turns up all kinds of recordings. The one that caught my interest is an album recorded by a jazz saxophonist collaborating with a string quartet, in which they take French Impressionist music pieces and use them as a basis for jazz-like improvisations. The result is beautiful, haunting, melancholy, and just strange enough to place it outside the usual classical music sound.
Despite my inability to understand what's actually going on musically, I love sound design. The software programs available for editing and mixing sound are just incredible (the same part of my brain loves video editing on the computer as well). Whether using music that a friend has written for a production, or taking cuts from previously existing tracks, sound design software makes it possible even for someone like me to create professional-quality sound cues for a show.
The sound for Hamlet is relatively simple. There are no long transitions — one group of actors leaves as another enters. But I've put in very short (on the order of five seconds) bits of music between each scene; just using simple fade in and fade out functions in the sound software. In some plays, I mix in a "whoosh" or cymbal sound at the beginning or end of these kinds of clips to give it some extra oomph or to cover an awkward edit. Some of these transitional cues are longer, to cover a pause at the beginning or end of a scene (Laertes takes a moment at Ophelia's grave, for example). All of these short clips are chosen specifically to land the scene that has just ended, and to begin the following scene with the right energy.
There are also several sound effects in the show. The most annoying for me is the fanfares and flourishes; I've spent way too much time searching for trumpet fanfares that didn't sound too medieval or too ridiculous. When the Players arrive, Guildenstern hears a flourish and says, "There are the Players." Instead of another trumpet, I researched the kind of horn a car in the 1890s would use, and found a sample on the web — it's a little silly, but I think it works. And I'm using a spooky tonal sound underneath the ghost, and in Hamlet's freezes. That particular cue is one I've used in multiple shows in the past (Marisol and The Diary of Anne Frank); it comes in handy.
The last line of the play is, "Bid the soldiers shoot." It seems an odd way to end the story. But the King is also always shooting off the cannon as a toast, and Hamlet complains about the King's excessive drinking and toasting to Horatio. So ending the play with those same cannons being shot off in an ironically inappropriate memorial to Hamlet seems right. The cannons bang three times, very loud, and a bit of music from the end of a track fades in with the third bang. The music has a long tail; it should let the audience know very clearly that the play is over.