The street call that became Mexico City's soundtrack

What began as a simple street advertisement has become one of Mexico City's most-recognizable sounds. The high-pitched call of scrap metal dealers, blared from loudspeakers mounted on passing trucks, is now embedded in the city's urban rhythm. In the first episode of a three-part series on the sounds of Mexico City, The World's Tibisay Zea explores how this everyday cry became a cultural landmark.