Workers look at traffic congestion, caused by detours, from an overpass which is under construction on the national highway 8, in Gurgaon, a suburb south of New Delhi, India. Traffic woes continued for commuters on the highway linking Delhi to Gurgaon despite the opening of two overpasses Tuesday. As carmakers sell more vehicles globally, they're changing horns to comply with various international noise laws.

Cars have gotten a lot more advanced in the last few decades, but at least one part — the humble car horn — has remained virtually untouched. Until now.

As carmakers sell more vehicles globally, they're changing horns to comply with various international noise laws.

They're using different materials to save weight and improve fuel economy.

And they're making horns more resilient for markets such as India, where horns are used much more frequently than in the United States.

Cars have had horns since the early 1900s, when the distinct “ah-oo-gah” of the Ford Model T first won America's heart.

Horns are designed a little differently these days, but the principle is the same: Electrical current flows through a copper coil in the horn, making a magnetic field.

The field makes a flat, circular diaphragm inside the horn oscillate, and the oscillation makes the horn's sound.

Horns may play one sound or may come in pairs to create the mellow chord that's most familiar to U.S. and European buyers.

Car companies used to offer different horns depending on the vehicle. In the 1960s and '70s, for example, Cadillacs had optional horns that played a C and D-note combination, rather than the usual A and F-note one.

But to save money, car companies now buy generic horns from third-party suppliers that can be used across their lineups.

Even when they get generic horns, carmakers still play a big role in determining how the horn will sound.

Victor Rangel, Ford's engineer for global traffic and security horns, finds the best location for the horn in each vehicle and figures out how to secure it. The placement of the horn and the brackets that hold it have a significant effect on the sound, he said.

“We look for the right sound for every vehicle ... kind of like an orchestra conductor, directing a really small wind section,” Rangel said.

Rangel's job has gotten more complicated as Ford has introduced vehicles that will be sold worldwide, like the subcompact Fiesta.