• Innovative speaker locations help produce a cutting-edge sound field.
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Date:31 July 2010 Tags:, , ,

Car accessories… Compiled by the editors, popularmechanics@ramsaymedia.co.za

Perfect sound on the move
Having set new standards in car-fi with specialists Bose and Bang & Olufsen, Audi’s in-house audio buffs are working on what could be the next revolution in sound

Peter Gleim’s eyes light up when he cranks up the volume. The engineer works in Infotainment Development at Audi’s headquarters in Ingolstadt, where he heads the Sound Concept project. His test subject is a Q7 sport-utility that looks dead standard on the outside. On the inside, it’s actually a rolling hi-fi studio that takes a radically new approach.

The idea behind the Sound Concept is a physical principle called wave field synthesis: the front of any individual wave can also be considered as superposition of individual waves. In the world of acoustics, this means that a sound wave can be recreated by a multiplicity of small sound sources placed closely adjacent to one another along the wave front.

The principle was first put into practice by Dutch scientists in the late 1980s, and it can be experienced today in a movie theatre in Ilmenau, in the German state of Thuringia. Each of the 192 individual speakers at the Linden Lichtspiele cinema is driven separately by a fast computer – at the precise moment in which the virtual wave front would pass through its point in space. Some signals are delayed by milliseconds, depending on the location of the speaker. Each moviegoer experiences perfect audio spatialisation in optimal sound.

It’s all around
One of the driving forces in the field of wave field synthesis is the Fraunhofer Institute for Digital Media Technology (IDMT) in Ilmenau. Audi began its development work in collaboration with the IDMT five years ago. The current status of the project is the Q7 prototype. A powerful amplifier takes up most of the space in the luggage compartment, and hefty cables connect it to three PCs in the workshop.

Installed in the Audi Q7 are 62 speakers – five woofers and five tweeters plus 52 mid-range speakers in the instrument panel beneath the windscreen, in the roof pillars and in the doors. Five units are integrated into each door sill. Specialists made cutouts in the sheet metal, fabricated new bezels and lowered the interior door release handles.

“Prepare to be amazed,” says Gleim. There’s that gleam in the eyes again as he reaches for the volume control. A wall of sound issues from the speakers – an artful mix of music, traffic noise and animal sounds. A female narrator guides the listener through the acoustic hubbub, dancing past on the right and at other times on the left. All the while, the listener’s ears are surrounded by the sounds of driving cars and roaring lions. A marching band seems to march from side to side through the Q7 before, finally, a helicopter flies a lap around the cabin below the headliner.

“That is specially created wave field material,” says Gleim, “comprising up to 32 tracks, with specific spatial information for each of those tracks.” You can’t buy anything like this –because there are no playback devices for it. Outside of the movies, that is, where film studios have caught on to the system.

But wave field synthesis is not dependent on special material to demonstrate its strengths. It also coaxes entirely new acoustic images out of conventional stereo signals. As Gleim explains, “We can simulate any wavefront. With stereo, we can generate a sound as if the two speakers were located far outside the car. And we can add any desired spatial impression computationally – not as a sound effect, but as a mathematically precise simulation.”

He plays a convincing sample: the vocals come from far off to the left, seemingly from the corner of the workshop, while a guitar plays in the other corner. It’s the same regardless of whether the listener is behind the wheel or on the right rear seat. Sound quality is always first class – with sparkling trebles, crystal-clear midrange and dry bass… even the slight buzz as the guitarist’s fingers hit the strings.

Put to the test
For an automotive company, Audi has accumulated an unusual amount of broad-based know-how in hi-fi technology. It began collaborating with the upscale American supplier Bose a good 20 years ago; the collaboration with Danish sound wizards Bang & Olufsen began around the turn of the millennium. By 2005, a B&O system was offered in the A8 luxury sedan (it’s now available in the Q7 as well).

How close does high-end car sound come to the reality of the recording? “The determining factors are always the installation locations in the car and the quality of the components,” explains Gleim. “When you order a car with the advanced sound system, you get the best speakers available anywhere. Many of them have membranes made of a glass fibre composite, which has a very natural and linear sound.”

Pure sound, though technically feasible, is not necessarily desirable. “A linear frequency response in the car would be boring,” says Gleim. That’s because the tight interior inhibits the sound from spreading out as it would in a living room. Seat cushions and upholstery absorb sound, so low frequencies need boosting. Electronic fine-tuning – the tweaking of the algorithms in the sound processor – handles this.

Below the high-end and premium systems, Audi offers its own sound systems designed in-house. The Electronics Centre established at the company’s Ingolstadt plant in 2003 includes a sound laboratory, where the sound systems undergo rigorous testing during development.

The laboratory features equipment valued at nearly R100 million – from the microphones and the special custom-developed amplifier test bed to the laser vibrometer. The latter uses a laser to scan the surface vibrations that occur on the speaker membrane, the speaker housing or the door in which the speaker is installed.

Speakers are analysed at the Audi sound laboratory in a testing room, which is a room-in-room construction. The testing room is mounted on thick elastomer bearings and is completely decoupled from the rest of the building – a necessity, given its direct proximity to a roller dynamometer.

All six sides of the testing room feature large glass fibre wedges covered in silk that break up the sound. A floating wire lattice serves as the floor.

The testing room is acoustically dead. The room is also often used to refine operating noises in the cabin, for instance to fine-tune clicking rotary knobs and switches. “As far as we know, none of our competitors have such a facility,” says Gleim’s colleague, Wolfram Jähn.

Listen up
Detailed instrumented tests and comparisons allow the sound development engineers to define detailed specifications for speaker suppliers – but there’s still room for subjectivity. Whereas the testing room is used for mathematical analysis, the adjacent listening room is tailored for the subjective experience. It, too, is an acoustically optimised room-in-room construction – the special wooden double walls backed with insulation only allow the desired linear reflections. The precisely calibrated high-end sound system installed here costs around R9 million and its vacuum tube-based end stages are the size of small refrigerators.

“The listening room is our acoustic magnifying glass,” explains Jähn, “where we check what really is on a CD or DVD. This is important because your ears quickly get used to a sound and sometimes interpret errors as interesting effects. We test our sample speakers blind. We can compare them to the optimum and reset our ears.”

Audi’s head of sound development, Denis Credé, says the Sound Concept has significant implications. “Our goal was to show what is technically feasible – to explore the limits,” he explains. “What we are learning will be integrated into the sound systems of tomorrow. It’s like racing: a lot of what is first tried out on the race tracks of this world later shows up in modified in production vehicles. The Audi Sound Concept project is like racing for sound systems.”

Source: Audi

Stay focused
It takes only a moment’s inattention: divert your gaze from the road to check the radio or your sat-nav, or take your hands off the wheel to adjust a setting, and you significantly raise your chances of becoming another accident statistic. In fact, says automotive electronics developers Springteq, this is one of the more significant causes of road collisions.

In the US, it’s been estimated that the cost to society of what can be called “driver inattention” is estimated at nearly R2 trillion. That country’s 6 million-plus car collisions a year result in more than 3 million injuries and 40 000 deaths.

One of the main reasons for driver inattention, says Springteq, is that the human-machine interface (HMI) for various devices is not positioned suitably, or are scattered in different locations inside the car.

That’s motivated improved ergonomic design of cars – including the implementation of the head-up display (HUD), a technology familiar to fighter pilots. The system has been in automotive use for some years, both in cars and on motorcycles using specially equipped helmets.

Problem is, expense and complexity has limited the information that can be displayed, and in general it’s also mostly found on premium models (although it’s becoming more widely used). Taiwan-based Springteq is hoping to change that with WeGo, the world’s first product to integrate satellite navigation and a head-up display in an all-in-one design. The driver sees a virtual image of the information, projected about a metre ahead.

The compact projector unit, which mounts on the dash, has a protective coating and heat-dissipating design that make it suitable for hot or cold conditions. It projects an 11 cm image, and features 400 x 240 resolution and a 500:1 contrast ratio. An optical sensor adjusts brightness automatically depending on ambient light levels.

What Springteq calls reflective image display technology eliminates the need to adjust focus. Power is supplied by a cable that plugs into the vehicle’s cigarette lighter or accessory socket.

Running Microsoft Windows CE, the device comes with 2 GB of built-in flash memory, expandable using SD memory cards. An RFbased wireless remote control is mounted on the steering wheel.

Springteq also offers the smaller WeGo mini with similar specs and a 9 cm virtual image from a 320 x 240 resolution projector with 10 000 cd/m2 brightness and 500:1 contrast ratio. Expect to see the device on the market by yearend. For more information, visit www.sprinteq.com

Tyres to go
Instead of having to drive out to a fitment centre, it’s now possible – in Johannesburg, at any rate – to have them come to you. A new mobile workshop, Tyres in Transit, travels to the customer for fitting and balancing. Even at home, if need be.

Fitted with state-of-the-art equipment, Tyres in Transit obviously cuts operating costs substantially. According to owners Kieren Quarmby and Kenneth Panayiotides, that could save the customer up to 30 per cent. All makes of tyre to fit all popular makes of car can be ordered.

Onboard equipment includes a tyrechanging machine capable of handling all tyre types and sizes without damaging rims, digital wheel balancing equipment, rubberised jacks to ensure that the vehicle’s underbody is not damaged, and an onboard generator and compressor.

Tyres in Transit can be contacted on 082 909 TYRE (8973) or at www.tyreintransit.co.za

Find your way…inside
Satnav systems can take you just about anywhere in the world with exceptional accuracy. But once you reach your destination, what then? Unlike what the Hollywood version of life might suggest, GPS satellites can’t see inside… yet. Now, research and technology specialists at BMW are working on ways to get around multi-storey car parks and enclosed buildings, even if you’ve never been there before.

The experts are unlocking completely new potential for navigation in the microNavigation research project. A detailed large-scale map display allows complex enclosed destination areas to be visualised – areas not covered by road maps in today’s navigation systems.

Even outside the vehicle, a mobile unit guides drivers to their desired destination and back to the vehicle. “The realistic visualisation of a building like a complex multi-storey car park by means of a microNavigation card in the Central Information Display of the research prototype gives the user a clear navigation and information advantage that goes significantly beyond the conventional scope of a road navigation solution,” explains Carsten Isert, project manager for microNavigation at BMW Group Research and Technology.

How it works. Drivers are able to download information about their destination in advance on their home PCs. If there is a microMap for the destination area, the driver is offered this automatically and can select a destination within the micro- Map. This destination is automatically transferred with the map data to the Car accessories vehicle and augments the navigation available there. (In future, it will also be possible to download microMaps at will while the driver is on the move.)

Researchers have also developed lane-specific positioning for the vehicle by networking camera information, GPS coordinates and map data. The driver is guided to the desired destination on a lane-specific route – for example a free parking space near the lift in the best position. Detailed maps in combination with precise carpark positioning provide support for drivers in finding their way around car parks and during the journey. After parking the vehicle, the data can be transferred to the driver’s mobile device (picture, left). This handheld then provides continuous navigation and helps drivers to navigate on foot in complex and unknown destination areas. “microNavigation gives drivers tailor-made navigation during the journey and at the destination and thereby significantly increases confidence and convenience,” adds Robert Hein, head of Navigation and Data Services of the Future at BMW Research and Technology.

– Source: BMW

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