Holiday music is the first
broadcast of the season. Much like the sudden alert of spring birds, the forces
that schedule, produce and filter Christmas hymns from back catalogues and
metal shelves in storage lockers out to 8 inch mono white grilled speakers
beamformed onto precisely calculated endcaps are a fantastic mystery that is
never asked to reveal itself. The truth is surely offensive, some pressed shirt
with a copy of SPSS pastes the predicted launch dates and harmonies into a memo
and forwards it to General Marketing. I've seen their mood circumplex for every
chromatic jingle plotted over revenue-- it's in a Microsoft Office 95 file, the
fonts look awful and only prints on legal paper. Rest assured that they've ran
the numbers-- they have the data. It's the only genre that lets musicologists
and A&R guys sit in the same room.
As a result, whether we participate or not, we are trained to associate the march from car to heated revolving door, from family pie to adjoint family pie, from ghost tree stand caravans to footprints of dry brown needles leading to the trash in January with the twee pasture of treble and tines and abrupt key modulation, led along on our heartstrings by wooden horses. X, you, times n, a projection through some unknown (until now) auditory stimulus, equals Y, a fond memory of everyone in a sweater. X and Y jitter irretrievably and tragically over the years, but n, static and full bandwidth, holds them together. I always liked to think of every sound, every instrument, every vocal phoneme and every delay tail in Phil Spector's classic "A Christmas Gift For You" as some hidden variable linking some version of me to some imperceptible holiday memory. Played as it is, it's every holiday I've had and still holidays I've yet to experience.
So then what is special about Christmas music? Let's take the objectivist view-- that there is something in the composition, construction, timbre or production in every popular Christmas song that makes it fit into the genre. Some predefined, baked in, Chomsky grammar style language of melodies and instruments. So play a Christmas song to someone who's never experienced a Christmas before. What do they feel? Do they rush out and buy spray-on snow? I never got around to doing the study. What I could do is try to distill holiday music down to its barest essentials. My hypothesis was that if we could figure out the dominant components of Christmas music, and train a system looking only at the audio to make more of it from those components, and if that new music passes the Turing test of the general public considering it Christmas music, then yes, we've cracked the code -- we can have Holiday Forever, a Singular Christmas.
Methodology
The recipe for generating this Eigenmusic ("synthesized music representing the maximal variety of the input music") was cooked up in 2003 as the live radio station "Eigenradio." It was a hilarious joke if you laughed at beehives, pleasing if you liked electric closets. Here's what the process is: you parameterize music into some set of features (pitch content, frequency response, high level structure, etc) and set some rate -- say a set of features every 100 milliseconds or four beats. You then pass those series of features to a popular statistical algorithm that tries to remove dependence among variables in the feature-- removing "redundant" information-- perceptual compression. Repetitive structures such as beat and harmony are whittled down to a representation that can always expand back later.
With this new compressed representation we have some powerful new tools. We can reduce two songs and see how close their representations are-- since we've removed some unimportant noisy stuff it works better than comparing the whole slow song. We can also tweak the representation and play it back again. Dehydrate a tune into two numbers, you'll probably get a measure of loudness and some measure of the most dominant low frequency, these are now synthesizer knobs you can tweak and compose around.
The fun stuff happens when you take more than one song, compress them all as a unit, and then re-create the original again, play it back. What you've got is the computer trying to spin around all the things it heard that it thought were important about lots of music. But always remember-- what a computer thinks is redundant are the very things we rely on musical enjoyment- repetition, patterns, harmonies, beat -- and what it thinks are important are things we would never want to listen to alone.
So A Singular Christmas is the
reduction of dozens of holiday songs, from grim coffee shop collections to
poorly recorded indie one-offs. Dozens of holiday records went into the
machine, and out came the sixteen tracks you can hear today. We synthesized those
tracks by randomly permuting those tweakable knobs over two weeks of sixteen
computers blithely ignoring any real work; each one rendered about a dozen New
Holiday Classics. As for the role of composer, maybe semi-conductor-- I locked
myself and family up in a darkened studio on the top floor at MIT, we turned up
the speakers, played every track in a row, and I hovered my index finger over
the Delete key. There's not a single window in that place, but I'm sure it
started snowing.
Brian Whitman, September 2006