COMING TO THE NORTH AMERICAN INTERNATIONAL AUTO SHOW IN JANUARY, 2014:
Dynamic Sound Technology from Faurecia Emissions Control Technologies
Exhaust Dynamic Sound Generation
On some diesel exhaust lines, control devices that are meant to slash emissions have had the effect of nearly completely muffling the emerging sound. The result is a premium car that is characterized by high power, high torque and a high price sounding like a tiny cousin.
Faurecia has developed a dynamic-sound-generation system that restores the voice of powerful diesel vehicles. It will be displayed at the 2014 North American International Auto Show. The technique focuses on the end of the exhaust line, next to the tailpipe, where the manufacturer places a speaker encapsulated in a metal or plastic housing. The vehicle’s engine electronic control unit (ECU) activates the speaker, prompting it to produce specifically designed sounds. The ECU itself determines the volume and type of sound to be generated, all depending on the vehicle’s speed and engine load. The resulting sound is nearly indistinguishable from that of a powerful gasoline engine.
This clever Faurecia technology benefits not only the consumer but also the designer, who usually is locked into a specific set of specifications for the exhaust that are extremely difficult to change late in the design process. With dynamic sound generation, however, the exhaust sound can be shaped at any point in the overall vehicle design, even at the last minute.
Exhaust Dynamic Sound Cancellation
Car buyers who choose dual turbo-charged gasoline-powered vehicles have the reverse problem: too much noise emerging from the exhaust. For these vehicles, Faurecia has invented what amounts to noise-canceling headphones for the exhaust system. Just as with dynamic sound generation, a speaker is installed near the tailpipe; but, through an algorithm integrated into the ECU, the speaker in this instance generates a sound frequency that is nearly the precise opposite of that which the exhaust is producing at any given moment.
As the driver speeds up or slows, the ECU monitors the exhaust noise frequency and alters the sound waves that the speaker produces to keep the opposite frequencies in sync. Most of the “battling” frequencies cancel each other out, leaving an audible but much lower level sound from the exhaust system. The speaker/ECU system works equally well on conventional vehicles and hybrids to cancel out exhaust noise when the gasoline engine runs.
After sound cancellation, the ECU can use the same speaker that masked the irritating noise to produce a more pleasing sound instead, an engine exhaust sound that enhances the image of the vehicle. The sound-altering algorithm may be integrated into the vehicle’s engine ECU or may employ a standalone ECU module. Faurecia offers the complete range of sound design technologies, from ECU to speaker and canning. Faurecia is preparing its dynamic sound technologies for the 2017 model year, and numerous global automakers already have conveyed their interest in the system for premium and mainstream vehicles.
Demonstrating Exhaust Dynamic Sound Design
At the North American International Auto Show in Detroit, visitors to the Faurecia exhibit will be able to use an iPad to play various sound signatures that begin with full exhaust sounds and then cancel that noise, adding the sounds of a 6- or 8-cylinder engine. Just outside of Cobo Center, Faurecia will position a live demonstrator vehicle to show how dynamic sound cancellation and dynamic sound generation function in a real passenger car.