How New Cars Are Getting Better Through Sound Engineering



"The loudest sound you ever hear is the first rattle in a new car."

Fire up the new Ford Shelby Mustang GT500 and you're greeted with the sort of raucous exhaust note that would make a Harley-Davison owner quiver with delight. Slip inside a Lexus LS460 and it'll be nearly as quiet as a tomb.

While features like design and performance help define a brand, few things distinguish a product's character like sound. So, it's no surprise that manufacturers are putting more effort than effort into managing vehicle sound characteristics.

But, "It's not just about how loud a car is," suggests Kara Gordon, who oversaw noise-related work on the 2013 Chevrolet Malibu. "The quality of the sound also matters. And even little things can have a big impact on your perception of a vehicle," she says, suggesting, "The loudest sound you ever hear is the first rattle in a new car."


Paul EisensteinPaul A. Eisenstein is Publisher of TheDetroitBureau.com and a 30-year veteran of the automotive beat. His editorials bring his unique perspective and deep understanding of the auto world to Autoblog readers on a regular basis.



The three biggest sources of unwanted noise come from the wind, the road and the engine compartment.

Traditionally, automotive engineers took a pretty straightforward approach to dealing with what was routinely referred to as the "N" in the trio of attributes known as NVH – short for Noise, Vibration and Harshness. And, indeed, all three go together. Reduce vibrations and harshness and noise usually drops way down, making your vehicle a lot more pleasant to drive.

The simplest way to deal with unwanted sounds is to stiffen up the chassis, add insulating foam and blankets and perhaps turn to trick features like laminated side glass. It also helps to improve a vehicle's aerodynamics, suggests Vishnu Jayamohan, chief North American product planner for the 2013 Nissan Altima, who notes that the three biggest sources of unwanted noise come from the wind, the road and the engine compartment.

Aerodynamics, of course, serve a dual purpose since the slicker a vehicle's shape the better its fuel efficiency. So you're seeing makers invest in more sophisticated technologies like the full underbody pan on the Chevrolet Malibu Eco.

Mirrors are a particularly difficult challenge as one of the most significant sources of wind noise, which is why Chevrolet downsized the new Malibu's mirrors and Ford has mounted them on the sheetmetal, rather than the window pillar of the new Fusion. Those odd blisters on the Nissan Leaf headlamps, meanwhile, direct air away from the battery-car's side mirrors.

Simply tossing mass at the problem isn't the answer.

Getting noise under control is a particularly difficult challenge with electric vehicles because of what engineers call the "stumps-in-the-swamp syndrome." With all the familiar engine noises gone, you're suddenly aware of the gravel crunching under tires, the whirring of motors and the whistling of fans.

Simply tossing mass at the problem isn't the answer because the heavier an electric vehicle gets, the shorter its range. Then again, the same goes for even a mainstream, gasoline-powered vehicle like the Altima, says Nissan's Jayamohan. The fourth-generation sedan is expected to be the lightest model in the midsize segment – and deliver the highest highway mileage rating.

So, to bring noise levels under control, Nissan had to take some creative steps, such as the use of a new lightweight sound barrier in the headliner made from a modified version of 3M's familiar Thinsulate material. It also borrowed a trick from some of its competitors, using a flocked plastic under the wheel wells that doesn't resonate when splashed with rain or pummeled with gravel.

Automotive engineers are no longer limited by NIH, or the Not-Invented-Here syndrome. They're even lifting ideas from the aerospace world. Honda is one of several makers that has adopted the same basic noise cancellation technology that makes it so much more pleasant to fly these days. But instead of relying on tight-fitting headphones, the Accord sedan and Odyssey minivan uses its speaker system to cancel out some of the more unpleasant noises that would typically echo through the cabin.

The 2013 Lincoln MKS offers an interesting twist on the noise cancellation concept. In this case, engineers wanted to not just cancel out unwanted road noises but also enhance the sound of the sedan's engine.

Settle back into your seat and enjoy the sound and the fury. It's likely been carefully tuned for your enjoyment.

That's not uncommon. Porsche and Ferrari, to name two exotic brands, have come up with various ways of beefing up the sound of their exhaust, in some models literally piping the sound into the passenger compartment. But Lincoln's approach is to amplify the sound on the front speakers, just enough that it appears you're actually hearing the engine itself.

You can expect to see manufacturers make even more extensive use of active noise controls in the years ahead, though it won't replace good engineering and more traditional solutions like sound-deadening insulation or laminated glass.

Whatever the approach a manufacturer takes, the results can be significant. It's not uncommon to see the latest models deliver noise level reductions of three, six, even nine decibels. That may not sound like much, but sound is measured logarithmically, so those numbers mean cutting your original noise level to half, a quarter or an eighth. And that means that even in the highest-power muscle cars, like the GT500, you can hold a conversation at highway speeds – unless, of course, you've got your foot pressed to the floor. In that case, settle back into your seat and enjoy the sound and the fury. It's likely been carefully tuned for your enjoyment.


Paul EisensteinPaul A. Eisenstein is Publisher of TheDetroitBureau.com and a 30-year veteran of the automotive beat. His editorials bring his unique perspective and deep understanding of the auto world to Autoblog readers on a regular basis.




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    • 1 Second Ago
  • 14 Comments
      Making11s
      • 2 Years Ago
      Unless I have a performance-oriented car (or even one just badged that way), I don't want the engine noise amplified, and even then, I'm not sure I do. However, I do like the noise cancellation idea and have enjoyed my experiences with it so far. As for other unwanted noises, I have fixed many squeaks and rattles by removing the noisy part and reassembling with a few rubber washers instead of screws alone. However, I have never had that sort of problem before 60,000 miles in any car domestic or import.
      • 2 Years Ago
      [blocked]
      car-a-holic
      • 2 Years Ago
      Too bad Mini thinks rattles are a sound worthy quality...... My mini had more rattles after 7k miles than you would believe. The stereo could not defeat them!.... Haha
      johnmichael.jfc
      • 2 Years Ago
      Meanwhile over at Audi where they actually have a guy ride in the trunk during testing to listen for unwanted noises... Our 1992 100 CS Quattro never rattled, and our 2004 A6 Avant only started with a tiny rattle this year from some loose trim. Even the old Volvo wagons we had didn't rattle. My 2006 Mazda 6s on the other hand took me a year of NVH trial and error to get all the rattles out.
      telm12345
      • 2 Years Ago
      Smart lady! My first car was a Corolla, never heard a sound. Second car was a forester, a week later the moonroof started making noise. I am not here to start an argument about Toyota vs. Subaru, because I still love them, but definitely made a quick impression...
      ehisforadam
      • 2 Years Ago
      I think the other comments, and this article to some extent, are missing the point of the use of resonators and engine noise over speaker systems...it's not just about how loud the engine noise (or just about any other sound from door slams to motor noise) is, it's about sound quality. As an automotive engineer, that's the big concern. An engine may have lower sound pressure (dB) but the quality may be poor because what's left is higher frequency which is objectionable so you use other means to tune that out. There are all sorts of sound quality metrics used to try and make qualitative judgements, but it's really pretty difficult.
        k_m94
        • 2 Years Ago
        @ehisforadam
        I agree, but the idea of cancelling engine noise through sound deadening then having to route it back (resonated or worse synthesized) again is a bit wierd. You wouldn't attach your steering wheel to a crank generator, whose rotation would turn into electricity to power a motor turning the steering mechanism, even if it did offer some nifty options, right?
      texascclp1445
      • 2 Years Ago
      Cranking up a GT500 is nowhere near the aggravating noise of a Harley. GT500's sound good. Harleys sound like they are always out of tune due to the less than 90 degree layout of the engine. Dumbass reporter.
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