I’m in Oaxaca, Mexico again for some meetings. I’ve been listening to the sounds of the city: buses, trucks, dogs barking, horns beeping.
Most houses in urban Mexico use propane gas for cooking and heating water. This gas is supplied in portable tanks—when you run out, you exchange your empty tank for a full one.
This is made easier by the fact that the gas man goes up and down the streets with a truck full of tanks. You hear him coming from a ways off because he has a chain of steel rings dragging behind the truck, and he beeps his horn twice every 20 seconds or so. Ching-ching-ching-ching-beep-beep is the gas man.
So as not to be mistaken for the gas man, the garbage man has a school-house bell on his truck that he rings as he goes along. Ring-a-ding ring-a-ding. Get your garbage out to the curb.
The knife-sharpening man comes on a bicycle with a pedal-powered grinder on the front. He blows a shrill whistle: tweet, tweet, tweet.
Then you have advertising cars, mostly VW beetles with huge loudspeakers on the roof that play some musical jingle or some canned spiel to get you to buy something. The local supermarket chain has one going around with a catchy jingle that has a cow mooing loudly in the musical pauses. It gets your attention. During election season, the cars are everywhere, blasting away with pitches for candidates.
All of this more or less fades into the background of your consciousness, until you hear that particular sound you’re listening for.
You have to stay alert. You have to be attentive, listening with one ear, because you just never at what hour the gas man cometh.