New approach to in-car audio from Continental

CONTINENTAL has invented a new type of car audio system that ditches loudspeakers in favour of audio panels for better sound and less weight.

Its engineers, who have been battling noise, vibration and harshness (NVH) for years, have turned their expertise to producing wanted noise in the cabin, developing a new concept technology that can radiate sound waves throughout the interior.

“We have experts that know both the acoustic and the behaviour of materials used inside the car,” said Continental engineer Jens Friedrich, who was speaking during the Continental Tech Show in Hanover, Germany, which highlights the advances the brand has made in a wide range of automotive areas.

“Our everyday job is to cancel out noise in the car. Therefore we know how the materials behave. With that knowledge we have built up this sound technology.”Mr Friedrich said the system works like a classical instrument, such as a violin that has a part that has to be excited – the strings. The excitations are transferred over a bridge into the body of the instrument, the third part of the system.

“The body of the instrument radiates the sound,” Mr Friedrich said. “Here in the car we use the same principles: we have excitation, and the transfer of this excitation to the body and the body is our car cabin.

“But we do not excite the entire car cabin. We use several surfaces inside the car that already exist.”Like the flat plane speakers used in the past for home stereo systems, the Continental system uses flat metal that is excited by small modules. The metal can be built into many parts of the cabin, including the A-pillars, the top of the dashboard, the back of the front seats and the roof of the vehicle.

All the normal trimming materials are then laid over the metal to present a normal finish to the surfaces.

“Why the car-makers are interested is we can provide them with a weight loss of up to 90 per cent, depending on the conventional loud speaker system being replaced,” Mr Friedrich said.

“But also we can provide a volume reduction (volume of space required) of up to 90 per cent as well, because our components are smaller and lighter because we use existing surfaces.”A high-end system of loudspeakers can require between 10 and 20 speakers and these can weigh around 15kg and have a cubic capacity of around 30 litres.

A Continental system can weigh as little as one kilogram and require as little as one litre of space in the cabin.

Mr Friedrich said the large roof panel in the system was excited by a module only three centimetres in diameter and one centimetre high.

“Therefore, we can reduce the amount of wiring in the car and the amount of components that have to be assembled on the production line,” he said.

“For the designer, we can afford a higher degree of freedom to design these interior surfaces. We don’t need the loudspeakers anymore.

“I think the most important advantage is the sound itself. This system has eight actuators. The conventional system in this car would have 13 speakers, it’s a high-end system from Mercedes.”Mr Friedrich said the new sound system would also be accessible for small cars as the number of actuators can be reduced and still produce the right sound.

“A car manufacturer can have a system with less components and still provide a fantastic sound experience,” he said.

“A small system would just be in the doors and maybe the A-pillars. We could also the centre dash and maybe the beam across the top of the windscreen.”As well as entertainment, the new noise surfaces could be used to convey other sounds to the driver, whether it is the indicator sound or a warning sound.