Crahan and his team of engineers are part of a growing trend among automakers to improve the sensory experience of driving. In the 2007 model of the Infiniti G35 due out in November, for example, they spent over two years redesigning 80 percent of the engine parts to increase stiffness and dampen engine noise. The car also has a dual-stage intake and dual exhaust to improve the engine’s “melody,” Crahan notes.
“It’s like a pipe on organ,” he said. “Acoustic engineers spend their time optimizing the harmonics through the length of the exhaust, or the intake length and volume, to create a luxurious sound,” he said. Switching to the image of playing a piano note, Crahan added: “What makes it a rich musical experience is the harmonics excited in other strings from the one note you play, and we have acoustic simulation software lets us try out different scenarios.”
There are clear benefits to offering car buyers a quieter, or more melodic cabin experience, particularly in the luxury market, notes Jack Nerad, market analyst at Kelley Blue Book, a resource for vehicle information. The trend toward quiet is driven by the growth in ultra-quiet, gas-electric engined hybrid vehicles, and also by a desire on the part of manufacturers to differentiate their product in a competitive automobile marketplace, Nerad said.
“Manufacturers want every edge and quiet is near the top of every consumer’s wish list,” he said. “When you look at what people want in their cars, not everyone wants a cushy ride and great handling. But across the board people favor silence; they consider it a major benefit. So that’s why we are seeing a lot of attention being paid to car noise management, especially on the luxury end. And like most things that start out in the luxury segment, it’s making its way quickly to lower-end vehicles.”