September 28, 2012

News & Features

Beep beep! Expanding global auto market spurs updates to car horns

The Associated Press



Cars have gotten a lot more advanced in the past 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 U.S.


How horns work

  • Typically, an electrical current flows through a copper coil in the horn, making a magnetic field. The field causes a flat, circular diaphragm inside the horn to 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. buyers.

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 (see sidebar).

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 says.

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

Rangel's job has gotten more complicated as Ford has introduced vehicles that will be sold worldwide, such as the subcompact Fiesta. Now he has to consider noise regulations in various countries to ensure that Ford's horns can be used in as many markets as possible.

This summer, for example, Sri Lanka determined that horn noise levels should not exceed 105 decibels at a distance of 2 meters and 93 decibels at 7 meters. U.S. horns are typically 110 decibels.

Emerging markets such as India are also forcing horn design changes because drivers use their horns more often in heavily congested cities. Jason Wong, General Motors' lead global engineer for horns, says GM now uses tungsten instead of steel for the horn's diaphragm because it lasts longer.

Ford is getting ready to introduce a horn that will hold up better even if it's used a lot or if the car is driven over bumpy roads. Right now, Rangel says, car owners in Asia often replace their horns as part of their regular maintenance because they get worn out.

Horn design is affected by the U.S. market, too. Wong says GM recently changed the copper wire in its horns to lighter aluminum, which slightly improves fuel economy.

Wong says we're moving toward a world in which car horns will sound more similar. Until recently, cars sold in China and India often used disc horns, which have a sharper, more metallic sound, because they're smaller and fit better in the cars sold in those markets. But as companies bring out newer, larger models, they're transitioning to trumpet horns, which play the mellower chords familiar to Western ears. Chinese customers are receptive to the change, he says.

"Generally speaking, people want the loudest, best-sounding horn they can have, regardless of the region," Wong says.


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