291 lines
12 KiB
Plaintext
Executable File
291 lines
12 KiB
Plaintext
Executable File
sponsored
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motoring
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ford-future-sessions
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future-of-science
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8207064
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-----
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# Ford and the art of noise
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## Cars are quieter than ever - so you can hear all sorts of distracting
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noises. And how do you tell a supercar from a shopping car by ear? That's
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where the science of acoustics comes in, says Andrew English - or is it an
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art?
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![Ford's dedicated acoustic testing lab allows technicians to study squeaks
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and rattles. ][1]
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Ford's dedicated acoustic testing lab allows technicians to study squeaks and
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rattles.
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Andrew English 3:30PM GMT 16 Dec 2010
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Define a noise. High- or low-pitched? Harsh, soft, or refined? Loud, rhythmic,
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discordant, harmonious or just plain old cacophonous? Difficult, isn't it?
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They're all vibrations and all waveforms, but as different as waves on the
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beach and almost impossible to describe.
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You might say that, in reducing a car's noise, Ford's sound engineers are
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playing the role of King Canute in trying to hold back the waves, except (in
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both cases) it's much more complicated than that.
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Where the 11th-century Viking king was illustrating the futility of kings in
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the face of God's power, Ford's engineers really are attempting to stop the
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waves. They are also trying to reduce the size of those waves, prevent their
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transmission and even change their shape.
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Complicated? Let Frank Foehner and Ralf Heinrichs explain. Foehner is the
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noise, vibration and harshness (NVH is the industry's favoured three-letter
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acronym) supervisor on the C and D platform cars - read Focus and new Mondeo.
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Notice he's an NVH supervisor, not an NVH exterminator - his job is
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supervising sound, massaging it around the car so it becomes (almost)
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unnoticeable to the human ear.
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"Basically we divide the job into three elements on top of each other like a
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pyramid," he says. "The bottom of the pyramid is fundamental acoustics and the
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avoidance of error states such as booming, vibration or drumming. Then there's
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the middle of the pyramid, which is sound refinement and the balance of noise
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sources. The top part is the super-refinement, which is the quality of the
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noise and the brand identity."
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If you** read the panel**, you'll see that there's not much that escapes their
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scrutiny at the first level, but the middle level is almost as painstaking.
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Tyres are a major source of noise and "tyre tuning is extensive at Ford", says
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Heinrichs, a supervisor for vehicle sound quality.
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"Road noise is a major issue," he says, "the radiated noise from the tyre gets
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fed back into the vehicle structure." He explains how the acoustic laminated
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windscreen in the new Mondeo has helped reduce noise not just from the tyres,
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but also from the engine, bodyshell, wipers, the wind battering the screen and
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the windscreen itself.
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"An ordinary windscreen is a pretty good loudspeaker that sits right in front
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of the driver," he says. "The acoustic windscreen is a poor loudspeaker and
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that's what we're looking for." In fact that acoustic layered screen is
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responsible for a three- to four-decibel drop in high-frequency noise in the
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Mondeo's cabin, which is a significant reduction to the human ear.
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And it isn't just comfort and refinement Ford is looking for when it reduces
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cabin noise. Work done initially in the commercial vehicle industry,
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particularly by Volvo and Scania in the early Eighties, shows that a simple
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reduction in noise volume has a huge effect on reducing driver fatigue and
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maintaining alertness.
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So, better carpets, a bodyshell swaddled in more than an inch-thick interlay
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of sound-deadening material, advanced door and window sealing, undershields,
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belt seals and the acoustic optimisation of start/stop systems are as much a
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road-safety requirement as they are a marketing tool these days. But then
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we're at the third stage, the quality of that sound, and here's where it gets
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really strange really fast. "Not that you can miss any of these stages,"
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asserts Foehner fiercely.
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So what does a Ford sound like? "It's a quality of sound," says Heinrichs. "A
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growly note, a resonance with the engine order, but only under acceleration."
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Foehner adds: "It's a sound feedback to the driver, related to the power, so
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it's not appropriate to have this power noise in a car without the power."
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For that reason, the discussion takes place around the more powerful 238bhp
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EcoBoost engine in the new Mondeo, where Ford wanted a signature acceleration
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note. In other words, they put noise back in. The result is a sound symposer,
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a mechanical sound box with a membrane inside, which amplifies the
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acceleration note from this turbocharged engine into the cabin.
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It was WO Bentley who, on learning that an independent firm had taken up
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supercharging his 4½-litre engine, condemned the venture, saying it destroyed
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the characteristics of an engine never designed to take forced induction.
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When I mention this to Heinrichs, he laughs. "Well, now we have the solution,"
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he says. "With the symposer, people perceive the forced induction car to be
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more sporty!"
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But what of the future? What about hybrid cars and electric cars, where engine
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noise will not necessarily correspond to road speed, motor whine will need to
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be engineered out and pedestrians warned of the approach of these silent cars?
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Foehner and Heinrichs reassure me that reducing the NVH of a hybrid or pure
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battery-electric car is no lesser challenge than it is for a petrol or a
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diesel engine, but the field of artificial warnings is an interesting one.
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Nissan's battery-electric Leaf is next year's European Car of the Year and it
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goes on sale in March. To warn pedestrians of its approach it produces an
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artificial anti-phase noise, which sounds like a low growl. This sort of
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warning for crowded urban areas is already mandated in Japan and the US has
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legislation in preparation, with European authorities taking a keen interest.
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Volkswagen and Mercedes are convinced that their electric car's signature
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noise will be an important part of the brand identity and Heinrichs agrees.
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"This is a really hot area right now," he says. "Everyone is talking about it.
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Not just having a motor noise, but a modern noise that marks your vehicle out.
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Everyone is working on it, but no one is telling what they are doing, it's
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absolutely top-secret."
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So what are Ford…? "As I said, it's top-secret," he says, "but what I can tell
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you is that nobody really knows what will happen in this area or what the
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future will bring in, say, 10 years." Looks as if we're all going to have to
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wait, then. Just keep on listening, folks.
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### Ford's voodoo fundamentals
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Voodoo engineering and lots of rubber make all the right noises...
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"To truly reduce the noise we have to get the fundamentals right," says Frank
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Foehner. The science of noise, vibration and harshness engineering is advanced
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enough to know where sound is generated and how it is transmitted, but
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reducing both means that sound engineers need to be involved in every element
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of a new car's design at the very first stages of its inception.
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"We need to be in early," says Foehner, "to achieve the right package." That
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"package" is the voodoo engineering of a car that sounds exactly right, and
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includes the stiffness of the bodyshell, the type, geometry and placement of
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the suspension, and the material and design of the body and driveline
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mountings.
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Sometimes the sound engineers' requirements conflict with those of the
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dynamics engineers, and the subsequent compromises introduce some of the
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really clever stuff, such as semi-voided suspension bushes that remain stiff
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but don't transmit noise, or sound and vibration dampers, which use a
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rubbermounted mass to damp vibration and noise, such as the Mondeo's dual-mass
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flywheel, or the dynamic absorber on the front struts.
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"We like rubber," jokes Ralf Heinrichs half-seriously.
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[X][2] Share & bookmark
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[What are these?][3]
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* Share: [Share][2] [ ][4] [ ][5]
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[Tweet][6]
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http://www.telegraph.co.uk/sponsored/motoring/ford-future-sessions/future-of-
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science/8207064/Ford-and-the-art-of-noise.html
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Telegraph
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## [Future of science][7]
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* ### [Sponsored »][8]
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* ### [Motoring »][9]
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* ### [Ford Future Sessions »][10]
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[X][2] Share & bookmark
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Delicious Facebook Google Messenger Reddit Twitter
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Digg Fark LinkedIn Google Buzz StumbleUpon Y! Buzz
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[What are these?][3]
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Share:
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* [ ][2]
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* [ ][4]
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* [ ][5]
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* [Tweet][6]
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* ![][11]
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[The Hubble Telescope »][12]
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### [WIN! a new book about the Hubble Space Telescope's amazing
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discoveries][13]
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[![Light echoes from a red supergiant star, as captured by the Hubble Space
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Telescope. ][14] ][13]
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The Telegraph has five copies of Hubble: Window on the Universe by Giles
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Sparrow, worth £40 each, to give away.
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### [The Hubble Space Telescope: the big picture][15]
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For 20 years the Hubble Space Telescope has shown us amazing images like
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these. Giles Sparrow, author of Hubble: Window on the Universe, explains why
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it's a modern marvel.
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### [Images from the Hubble Space Telescope][16]
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[![Images taken by the Hubble Space Telescope from Giles Sparrow's Hubble:
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Window on the Universe. ][17]][16]
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Images taken by the Hubble Space Telescope from the book Hubble: Window on the
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Universe.
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[The new silicon? »][18]
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### [Graphene: our miracle material][19]
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[![Graphene is a planar sheet of carbon atoms arranged in a hexagonal pattern.
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Stacked graphene sheets form graphite, used in pencils. ][20] ][19]
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Graphene is harder than diamond, just a single molecule thick and conducts
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electricity. Kat Hannaford talks to the two Nobel prize-winning scientists who
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discovered it about why it could revolutionise everything.
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[1]: http://i.telegraph.co.uk/multimedia/archive/01786/mondeo_1786994b.jpg
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[2]: #
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[3]: http://www.telegraph.co.uk/technology/news/4590190/Share-this-article-
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What-are-these.html
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[4]: mailto:?subject=A Telegraph reader thought you would be interested in
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this article&body=Depending on your email program, you may be able to click on
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the link in the email. Alternatively, you may have to open a web browser, such
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as Firefox or Internet Explorer, and copy the link over into the address bar.
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%0A%0Ahttp://www.telegraph.co.uk/sponsored/motoring/ford-future-sessions
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/future-of-science/8207064/Ford-and-the-art-of-noise.html %0A%0AFor the best
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content online, visit www.telegraph.co.uk
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[5]: javascript:print()
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[6]: http://twitter.com/share?via=Telegraph
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[7]: http://www.telegraph.co.uk/sponsored/motoring/ford-future-sessions
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/future-of-science/
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[8]: http://www.telegraph.co.uk/sponsored/
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[9]: http://www.telegraph.co.uk/sponsored/motoring/
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[10]: http://www.telegraph.co.uk/sponsored/motoring/ford-future-sessions/
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[11]:
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http://i.telegraph.co.uk/multimedia/archive/01766/Ford_in_asso_1766175a.jpg
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[12]: http://www.telegraph.co.uk/sponsored/motoring/ford-future-sessions
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/future-of-science/8206698/Celebrating-the-Hubble-Space-Telescope.html
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[13]: /sponsored/motoring/ford-future-sessions/future-of-
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science/8206679/Win-a-copy-of-Hubble-Window-on-the-Universe.html
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[14]:
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http://i.telegraph.co.uk/multimedia/archive/01786/hubble1_1786847e.jpg
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[15]: /sponsored/motoring/ford-future-sessions/future-of-science/8206698
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/The-Hubble-Space-Telescope-the-big-picture.html
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[16]: /sponsored/motoring/ford-future-sessions/future-of-science/8207252
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/Images-from-the-Hubble-Space-Telescope.html
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[17]:
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http://i.telegraph.co.uk/multimedia/archive/01787/hubble3_1787067e.jpg
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[18]: http://www.telegraph.co.uk/sponsored/motoring/ford-future-sessions
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/future-of-science/8207121/Graphene-our-miracle-material.html
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[19]: /sponsored/motoring/ford-future-sessions/future-of-science/8207121
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/Graphene-our-miracle-material.html
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[20]:
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http://i.telegraph.co.uk/multimedia/archive/01787/graphene_1787024e.jpg
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