It's not unusual for film composers to make music out of organic sounds found in or related to the movie. Take Nathan Johnson's stunning Looper score which was built on a foundation of sampled clicks and pops that captured the film's steampunk creakiness. Or, more elementally, the typewriter rhythms Mark Mothersbaugh used for his Royal Tenenbaums score, emulating the film's anachronistic storytelling themes.

For Rat Film, a new documentary that explores Baltimore's complicated history (as told through the city's rat infestation), electronic artist Dan Deacon developed an elaborate system to get the rats themselves to make the music. Let's just say it's technical. But in this track-by-track breakdown, he explains just how he did it, the challenges of making music that's simultaneously uplifting and moody, and how he navigated seeming failure and happy accidents.



"At the onset of the project, [director] Theo [Anthony] asked me if I could make music with rats. After some thought, my brain landed on the concept of an enclosure made out of theremins (one of the first electronic instruments ever invented and played by hand gestures). As the rats moved from one corner to another, the pitch and volume would change and create these odd harmonies. I was able to record not just the sound, but a digital conversion of the voltage, which proved the most useful. 'Redlining,' a piece for a Disklavier player piano (a self-playing piano that takes incoming MIDI data from a computer), is one of the products of that rat theremin performance/experiment. Using the rat movements as rhythmic data and a rough pitch contour, I began the process of editing together my favorite sections and conforming the note data to a scale. I wanted the tone to be emotionally ambivalent, in parallel with the narration. I wanted the viewer/listener to project their own feeling from their reactions to the content Theo was presenting. The music couldn't be too steering or it would take away from the experience. This ideology was used throughout the film but I tried to most strongly apply it with this track."

"Horn Phase"

"This is one of the first pieces I wrote after seeing some raw, initial footage from Theo. The slow panning Google Earth footage of Baltimore thought of as a 'video game' was really disturbing to me. Sitting so heavy in the uncanny valley, I used the images' unrealness as inspiration for a hanging, never settling or resolving sextet of synthetic brass. It made me really happy when Theo paired the piece with those images."


"'Pelican' is the exact opposite of 'Horn Phase' and the piece that came with the most input from Theo. It needed the feeling of falling back into your chair with an all-too familiar disbelief, like a musical shaking of your head in disappointment. But it needed to be light and airy, laid back and calm. The brilliant guitarist Steve Strohmeier came in and improvised over a loose structure for a few hours, leaving me with a vast collection of perfect riffs to assemble into a small ensemble of somber guitars."


"'OCME' was the result of a mistake turned into a blessing at the end of an extremely long and trying day. Theo was over at my studio and we struggled with finding anything either of us felt happy with for this section. I was accidentally moving the MIDI data from the rat-theremin performance and dropped it into a synth-patch channel and all of a sudden these eerie, singing-saw-like sounds began coming out. It was a real ghost in the machine moment that I would never have planned if I tried."


"Some of the first footage I saw — and one of the only sections I wrote to picture — was the introduction of [a man named] Harold and the Baltimore City Rat Rub Out team playing ping pong. I wanted something that complimented the ping pong sounds and the rat brain clicks that color the sound design at cut points. Growing up, my parents owned and operated a small, two-person pest control company. Harold's viewpoints and outlook on life come across as very similar to that of my parents."

"Reed Clouds"

"'Reed Clouds,' a processed layering of several improvisations by one of my favorite musicians, Andrew Bernstein, was recorded in a large pantry off the kitchen in my apartment that I converted into an isolation booth. Bernie was over for a session to do some takes on another large project I was working on simultaneously. I asked him to improvise free, then to improvise over some loops I prepared. Afterwards, with all the various takes, I began altering and editing them into what I wanted to sound like a cloud or haze. As it was early on in the process, I sent it to Theo with no notes on placement and it lived in a few spots before eventually finding its home being paired with the pops of the rat brain and the images of driving through Baltimore."


"For 'Seagull,' I recorded cellist Owen Gardner in a similar fashion to the way I recorded Bernie for 'Reed Clouds.' A series of improvisations, first free and then directed, 'Seagull' is a layering of Owen's masterful playing of a series of 'seagull glissandi,' a technique which yields a beautiful cycling of artificial harmonics. I asked him to play these seagull glisses for an extremely long time (mostly for my own pleasure). After the session, I watched some of the footage Theo had sent over and got inspired to focus on these seagull glisses. I slowed and pitched them down, layered them and applied a series of effects. (I'm now just realizing the other project I was working on also has a song called 'Seagull')."


"'Calhoun' is a variation of 'Redlining' with a different voicing realized using vibraphone samples."

"Rat Poison"

"After watching the raw material Theo gave me, I learned so many details about rampant systematic institutional racism the city and JHU [John's Hopkins University] have been imposing for decades. It felt like a dreary, sickening haze imagining the boardroom conversations where people justified and normalized their practices. Using that reaction, I also tried to focus on the surface-level subject matter, the actual rat poison. Working towards a drugged-out, hazy feeling, I experimented with chords on a pillowy synth as the framework and then applied some rat Theremin data to a woodwind synth patch for the melodic content towards the end of the piece."

"Video Game"

"'Video Game' is perhaps the first piece I wrote for the score after watching the Google footage of Baltimore and hearing the initial narration Theo has in place about the video game. I really like how digitally corroded the images were, where the streets are growing up into the wheel wells of cars like asphalt weeds, the trees morphing together with the bricks of the row homes. It was a horrifying set of images and I wanted overly synthetic sounds to pair with the corrosion I was seeing."

"Harold's Lament"

"'Harold's Lament' is another piece for cello performed by Owen Gardner. One of my favorite parts of this recording is the sound of the creaking Ikea chair Owen was sitting on that I grabbed from my kitchen for the session. Beyond Owen's extended technique for kitchen chair, the piece is a structured improvisation, asking him to focus on extended techniques and effects, slowly drifting into a series of audio effects, and then layered with various other sections of the take."

"Map Overlays"

"'Map Overlays' is a companion piece to 'Redlining.' Another piece of player piano, sculpted from the rat performance session (which, I should note, is seen throughout the film). For a great deal of the rat performance, the rats huddled up into a corner and sat still, leaving the Theremins droning with only very slight variation. At times during the recording, it seemed like the bulk of the experiment was a failure. But after getting the data and seeing these slight variations I found them really inspiring to work with. I applied the sections of stillness to a single note on the piano and octave, and layering of the note would change whenever there was a fluctuation in their small, huddled movements. I really enjoyed the effect and I don't think I would have scored the section the same without it. We really had no idea what to expect from the rats and the Theremins. In hindsight, I couldn't be happier with the result of that experiment. Not only for the music it helped create and inspire but because it marked the start of an extremely rewarding collaboration and, more importantly, a strong friendship with Theo.

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