Mexico City is a noisy metropolis of more than 20 million people, known for its colonial church bells and relentless traffic. But amid the noise, it's also a place where sounds have meaning.
Millions of motorists rev their engines and bang on their horns. Dogs yap. Green Volkswagen Beetle taxis sputter.
When I first arrived in the city, the noise was a bit overwhelming. I'd step up out of the subway and be hit by the yelling, the whistles, the bells, the traffic. But slowly, I came to realize that there is a social order to this cacophony.
Take the sound of morning in my neighborhood. Right around dawn, the trash collectors rumble in in their hulking white truck. One of them jumps down and walks the block, ringing a large brass bell calling residents to bring out their garbage.
Later, young boys with wicker baskets of bread shuffle through, shaking high-pitched bells.
A knife sharpener rides by on his bicycle, blowing a whistle.
In the evening all across the capital, tamale vendors take to the streets. They play a warbly cassette that sings the praises of tamales from Oaxaca.
If you're not in the mood for tamales, you can listen for the sweet potato woman.
The yams, called camotes, are sugary, moist and too hot to hold.
They cook in the woman's stainless steel cart as she pushes it up the street. She runs the steam out a long whistle to announce her presence.
Some cities have a certain smell or a landmark or a vista. Mexico City has its own soundtrack.
Stoplights can resemble carnivals. Organ grinders — wearing beige uniforms allegedly fashioned after those of Pancho Villa's soldiers — crank antique music boxes.
Vendors walk down the rows of cars, selling everything from cigarettes to candy, bottled water to inflatable maps of the world.
Jugglers in clown-face makeup toss balls, hoops and flaming torches.
At first, the people crowding around my car felt intimidating — even a bit claustrophobic. Now, it feels like a dance. The newspaper salesmen sway to the sound of a German waltz. The squeegee boys with their filthy rags move in and out of the cars to the rhythm of the traffic lights.
And the barrel organs pop up at one light after another, pumping out the same melodies, almost all of which are horribly out of tune.
Millions of people in Mexico City work in the informal economy; markets can crop up just about anywhere.
Along one street near the Zocalo, or central square, half a dozen men are selling bras, towels and cheap soccer balls out of black garbage bags.
And there's a rhythm to the week: On Sundays, certain street bands show up.
They come banging on drums and doorbells. On cue, my children rush out to give them a few pesos.
The Mexican capital gets kicked around a lot. People complain about the thick smog, the intense traffic, the brutal crime. But if you listen just right, amid the chaos is a disjointed symphony waiting to be heard.