One recent morning, I started an endless "underwater" session on Brain.fm. My news shift flew by and I was noticeably more productive, writing a few more posts than usual and clearing my inbox before I closed my laptop for the day. Great, right? The problem is, I didn't feel that I was 'in the zone' like I do when I'm on a streak -- it felt like I was in a trance. It wasn't comfortable. That might have something to do with the fact that I subjected myself to nine hours of Brain.fm's trademark trick: low-frequency envelope modulations.
These amplitude modulations work based on "forward masking." Meaning, if you hit a snare drum, for a moment afterward your ear is less sensitive to everything else. "Amplitude modulations are helping you drown out background sounds while keeping the music at an overall even level," Woods explained. The low-end modulations sound like helicopter blades, a low thrum vibrating louder, then softer, between 10 and 20 times per second. If the modulations are too slow, like the bass drum in a 4-4 rock beat for example, you're pulled out of focus because your brain is anticipating each kick. Speed it up and your brain more or less stops caring.
"There's a good reason to care about amplitude modulation," Woods said. "You can go into the brain and poke neurons and you can see that they'll respond to changes in amplitude rate in a very specific way." He added that there are populations of neurons in the brain specifically tuned to react to the frequency modulation spectrum. "Which is why we care about them," he said.
Maybe that's why I don't fall into a trance-like state looping The Social Network. Because it's imperfect by design, my brain isn't constantly locked into focus. The lack of dense textures from "In Motion" and the absence of low-frequency amplitude modulations in "Carbon Prevails" actually do my neurons a favor.
Since 2013 I've listened to The Social Network 226 times via Google Play Music. That's not counting those first three years of listening on my now-dead desktop PC, a CD and the Halo 3-branded Zune for which I lost the charging cable.
The score keeps a movie about friends screwing each other out of billions of dollars moving at a brisk pace and Aaron Sorkin's machine-gun fire script grounded. Reznor's method for the record shed a few clues about why it works for me.
"We needed something that sounds like a spark of creativity, of acceleration," he said during a press tour interview in 2010. "You've got a good idea, and you want to follow it to its course. [It's] that excitement." During that same fireside chat, supervising sound editor Ren Klyce agreed, describing one song in particular as sounding "percolating, like wheels moving in [Zuckerberg's] head."
When Woods told me the album's fifth track, "Intriguing Possibilities," checked off all the boxes for desirable focus music I was caught off guard. It wasn't perfect (Woods said it could use more frequency modulations), but it's a "close match" for Brain.fm's AI-generated songs.
At first I didn't believe him. And then, embarrassingly, I had to quickly queue the song up so I could figure out which one it was. Even after all the listening I've done, I still can only associate names with album opener "Hand Covers Bruise" and then "Mountain King." The rest have bled together by this point; I identify them by musical passages, not names or track order.
I looped the song for an evening while working on this piece, and I felt similar to how I did after a day with Woods' music. Because it's only 4:24 long and doesn't loop well at all, I was keenly aware of each time it repeated, giving my neurons a break at a quick interval. The trance-like sensation wasn't nearly as intense as it was with the AI-generated tracks, but I felt it nonetheless.
Overall, Woods' analysis of The Social Network was that it's the best option of all my go-to music (with Darksiders II coming in close second), even if some songs didn't have any dense textures or enough spatialization. At this point, I'm so familiar with the music that any distractions from Woods' perspective as a first-time listener are moot. There's also the mental association I have with the album. Because I've made it my default task music for the past eight years, there's a Pavlovian effect and my brain knows it's time to buckle up. "If there's a track you've been listening to all your life and it's new for me, it's going to be more distracting for me because it's new," he explained. "People are different. Their experiences are different."