PLYMOUTH, Mich. - Graham Tompson was on vacation with his family when inspiration struck - or maybe it was just the headache his wife was getting from listening to the high-pitched whine of laser blasts coming from their children's video games.
Although the children were in the back seat with headphones on, the sound still leaked through enough to allow the pitch to fray her nerves.
But Tompson is not just another frustrated father. As senior vice president of auto supplier Collins & Aikman Corp.'s global product development division, he knows car interiors and the materials in them.
And he was convinced there was a way to capture and banish that whine.
'Every material in the car will have an acoustic impact,' Thompson said at the company's technical center. 'It does something. It reflects or it absorbs.'
The company has a patent-pending system it is preparing to offer automakers, one that traps unwanted sound through a perforated cover on vehicle interiors. Eventually, Tompson hopes to tune the system, finding out how to tackle specific sounds just by altering the pattern of the holes in the cover.
'Our job is noise management in the vehicle,' he said.
It is one of a growing number of plastics-based programs throughout vehicles - from the frame to the engine and from floor to ceiling of the interior - designed to entice consumers by offering up the right balance of sound.
They are the tricks of the trade that make a Lexus sound like a luxury vehicle, a Mustang like a muscle car and a Dodge Ram like a pickup.
That acoustic balance is gaining importance with automakers that are anxious to tweak their vehicles to improve sound quality and impress consumers with the atmosphere inside their cars, even if those buyers have no idea what gives their car either a sporty or solid sound.
'If you ask people, 'How are the acoustics in your vehicle?' they'll say: 'I've got a great stereo system. I've got a Bose or a six-disc, in-dash CD player,'' said Barry Wyerman, director of advanced materials engineering for Lear Corp.
'All the driver knows is whether their car is quiet or noisy. They don't know what's under it. You don't see any of it. The only time people comment on (acoustics) is if it's bad.'
FRONT SEAT SOUND
Plastics play a key role in those acoustics, from polyethylene acoustic barriers within the interior trim to the thermoplastic mat between the engine and passenger compartment.
There are injection-molded thermoplastic barriers inside the steel frame and hollow, reedlike resonators designed in nylon engine manifolds to change the pitch of the air as it whistles past.
'The acoustics requirements in autos have increased,' said consultant Robert Eller, president of Robert Eller Associates Inc. 'Acoustics are being considered earlier.'
No company controls the entire acoustics package. Instead, the sound design of the car is divided among suppliers.
There are noise issues from under the hood.
Sound travels from the wheel wells, where the tires meet the road. There is the mix of sounds outside the windows, from the hum of passing traffic to construction. And, Wyerman said, there also are the sounds that must cut through any acoustic barrier, such as ambulance sirens or a warning honk from a passing car.
Automakers typically set aside less than 10 percent of a vehicle's production cost for acoustics, but they are noting those sound qualities in advertisements.
'(Sound control) has always been an issue, but in the last five to 10 years, they've really started to ask pointed noise questions,' Wyerman said. 'Car and Driver may do a review and say that it's an affordable car, it's fun to drive - but if only it didn't sound like a truck.
'That's the kiss of death.'
PUTTING NOISE TO TEST
The growing interest in sound has prompted suppliers to invest in both acoustics research complexes and product research, so one day they can specify not only what types of sound environments consumers want but also why.
In testing facilities throughout Michigan's auto manufacturing base, companies have invested in echo chambers to check sound levels and recording equipment to determine how humans hear those sounds.
Sika Automotive, the Madison Heights, Mich., subsidiary of Sika Corp. of Zurich, Switzerland, has built its base around auto acoustics. It produces thermoset barriers to cover small holes in the auto body and its expandable thermoplastic baffles, which can absorb 60 decibels of road noise, said Greg Hopton, vice president for marketing with Sika's auto group.
The Occupational Safety and Health Administration estimates that a conversation registers at about 60 decibels; a power motor at a little more than 100 decibels; and the sound of city traffic, from inside a car, at about 85 decibels.
The baffles are injection molded to meet the shape of a vehicle's hollow frame, and snap into place early in construction.
Once the body is assembled, it goes through an oven to apply a rustproof coating. At that temperature, the foam expands to more than 1,000 times its original shape and effectively blocks sound from moving through the frame.
'They play such a key acoustical role, yet nobody knows they're there,' Hopton said.
But they are big business.
SOUNDS OF A BOOM?
Within the past year, Sika has opened a $12 million manufacturing complex in Grandview, Mo.; an $8 million, 30,000-square-foot acoustic test complex in Madison Heights; acquired Magna Group's business unit for baffles; and established a joint venture in Japan.
The push by automakers for suppliers to bring in complete modules also has passed a share of the overall sound design to those companies, Wyerman said.
A business supplying a headliner, for instance, needs to work not only with acoustic barriers within its expertise, but ones that will complement other companies' seats, flooring or door trim.
It needs to know if a loud hum in a third row of seats is from the floor or an open channel in the frame, he said.
'You could spend a ton of money plastering materials all over the place and not make a difference because you haven't stopped the leak,' he said.
Those concerns over sound are not just for the passengers in a car but also extend to the people outside it.
European officials have concentrated more on pass-by noise because of the proximity of cars to houses along narrow streets. North American consumers and legislators could call for the same sound-dampening standards, though, Tompson said. Those solutions are not as easy to find.
'We can't just fill an engine compartment with fiber absorbers, since that also impacts the airflow needed to help cool the engine,' he said.
Collins & Aikman hopes to have Tompson's perforated plastic sound-absorption program ready for the market within a year.
Lear has developed SonoTec AT, a thin composite thermoplastic system using recycled fibers, which combines with a thermoformable polyethylene backing to draw in and trap sound. The program can reduce weight in an insulation panel between the engine and passenger compartment to 4 pounds from 10.
The increasing interest in acoustics will make its way throughout the auto suppliers' community, Eller said, with more questions asked about how to control sounds on vehicles earlier during design.
'The car is now a mature product,' Tompson said. 'People expect it to run, so carmakers want more value added to the final product to help (buyers) decide which one they want.
'Comfort and pleasure make a difference.'