All week long, we've been playing this sound, and asking you to guess what exactly it is and where exactly in the Bay Area we recorded it.

This auditory guessing game is part of Audiograph, a crowd-sourced collaborative radio project mapping the Bay Area’s sonic signature. Audiograph tells the story of where you live, and the people who live there with you. Every Thursday, we tell you the story behind our weekly mystery sound on Crosscurrents, and here in weekly blog posts.

Listen above for the full answer...

CLAUDIA KELLERSCH: I've been nude in the Bay to Breakers every single year ... I'm wearing a little fanny pack where I'm hiding my underwear, and I have really good race running shoes. And I have a hat that says "Bare to Breakers!"

Congratulations to this week's winner, Matthew Smith!

Is there a sound from your life that should be featured on Audiograph? Call at 415-264-7106 and tell us about the sound of where you live.

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