Bop Spotter: Box installed high on Mission street pole, secretly recording songs

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It’s said that the walls have ears. Now, so does a pole in the Mission. 

Last Saturday, Riley Walz installed a box with a “crappy Android phone” and a microphone up on a pole at an undisclosed location in the neighborhood. It’s been picking up 10-second recordings of songs played on the street below, and feeding the clips to Shazam. More than 200 songs have already been identified by “Bop Spotter” since noon on Monday. 

As expected, there’s lots of Spanish music. So much so that Walz’s Google Chrome “thinks the site is in Spanish, and asks me if I want to translate it,” he said. Most of the recordings, however, are a chorus of honking cars, Muni buses, laughter, and muffled voices. 

Inspired by ShotSpotter, the police’s system for detecting gunshots, the 22-year-old Walz, who lives between the Castro and Twin Peaks, decided making Bop Spotter would make a “fun little weekend project.” It took about 10 hours of time and $100 worth of supplies to make, Walz said. 

About 95 percent of the code was written by ChatGPT, he said. Figuring out where to install the box posed the biggest challenge. There had to be a balance of natural light — to charge the solar panel that powers the phone — and free Wi-Fi for it to connect to. 

It’s also picking up a lot of pop and rap; well, who hasn’t heard Kendrick Lamar’s “Not Like Us” from a speaker on Mission Street? 

At 4 p.m. on Monday, it picked up someone playing back-to-back versions of Shakira’s “Hips Don’t Lie.” At 6 p.m. this evening, it recorded both “Cop a Chicken” by OJ da Juiceman and “Kop a Chicken” by Gucci Mane. The Shazam algorithm is apparently more fine-tuned than even Walz imagined, because it catches music that the human ear might miss, and can differentiate versions by featured artists.

Just after midnight, Vincent Woo, a Mission resident and board member of YIMBY Action, found and “Rickrolled” the box, playing “Never Gonna Give You Up” by Rick Astley. Bop Spotter’s description and the street noise he heard in its recording provided all the clues he needed, Woo told Mission Local. 

(He declined to share its location; that would ruin the fun. But if Mission Local’s managing editor Joe Eskenazi finds it, he plans to play “Gimme Shelter” by The Rolling Stones.)

I installed a box high up on a pole somewhere in the Mission. Inside is a crappy Android phone, set to Shazam constantly, 24 hours a day, 7 days a week. It's solar powered, and the mic is pointed down at the street below https://t.co/8D4yYNBPgu pic.twitter.com/pyYzUltJQX

— Riley (@rtwlz) September 30, 2024

Since its announcement on X on Monday morning, people around the world have reached out, saying they want to set up their own Bop Spotter, Walz said. In true San Francisco software engineer fashion, he’s now thinking about making a kit with DIY instructions for others to replicate. And the next time Walz is passing through Times Square on his way home to upstate New York, he’ll probably put up a second location to compare city soundtracks. 

People have also reached out to Walz saying that the songs Bop Spotter picks up aren’t representative of the Mission overall, just the preferences of those “crazy enough to play music loudly and subject everyone to their tastes.” 

But “they can influence what types of music people like,” Walz argues. Much of the music in his massive “liked songs” playlist on Spotify was found by Shazam-ing songs he heard in public spaces. 

While there’s no official next project in the works, Walz and his friends are often brainstorming stunts and inventions that run the gamut of silly to useful. Walz’s past work includes a fake steakhouse that lured in gullible New York City elites, and a random route generator, inspired by his time running cross country at Baruch College. The friend group is just trying to have fun and bring people joy, Walz said. The press follows. 

Their most recent idea? Build a speaker that blares “bless you” every time someone on the street coughs.