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Acoustic Innovation: The New e-sound for Audi e-tron Models

• The brand new developed sound profiles for their future e-tron models• A control device generates the sound based on signals from the car

• A speaker emits the sounds on the street

Editor’s Note: Watch a video and hear the noise of Audi e-sound in a video posted in our discussion forum thread about this subject.

The future e-tron models of Audi drive long distances on electricity and therefore emit virtually no engine noise. So that passersby can hear it in city traffic, the brand has developed a synthetic sound – the Audi e-sound.

The work of Rudolf Halbmeir is not typical for an Audi engineer. On his desk is a music keyboard, next to a computer screen, two mini-speakers and stack of music magazines next to these. “The sound of a car,” says acoustic engineer Halbmeir, “has similarities with music.”

Sound is a very exciting quality of a vehicle – one that you can indeed describe vocally, but even better to be experienced. Sound effects the gut, not the brain. Although the driver of a car listens to it, that person is only conscious of it in certain situations, though experiences constantly and it determines the driving experience with intensity. Sound transmits signals. Low frequencies show glimpses of strength and serenity, medium transport athleticism and agility.

All cars from Audi produce sound images that seem smooth and harmonious, expressing its performance, quality and solidity. “Good sound design is a complex issue,” explains Dr. Ralf Kunkel, head of Audi’s acoustics. “We have worked here for years and have learned much. We know how to increase pleasant frequencies while suppressing unwanted noise. ”

In our production series of cars, Audi currently makes the best music. In an electric-powered e-tron, the electric motor is removed from the equation since it operates at frequencies too low and too high for the human hear – the effect is less pleasant. The e-tron models from Audi have therefore a synthetic sound. Rudolf Halbmeir has developed it together with his colleagues and Dr. Axel Brombach Lars Hinrichsen.

Most of the work took place at the computer. Mix together sounds via software, monitor, evaluate, re-mix – the creative process Halbmeir recounts with much enthusiasm, because he is a songwriter in his spare time, a composer with his own recording studio that can play all the instruments himself. “I create emotional structures that did not exist before,” says Halbmeir. “This is the vehicle sound, not much different than in music. I follow my intuition; I have to try out ideas to see where they lead me. ”

What were the ideas? “In some science fiction movies I have found suggestions that were useful for certain frequency ranges,” says Halbmeir. “But in the real environment, there was nothing that sounded like it should sound like. If you compose music or sound, you have to do that which they themselves believe. As soon as we delve into compromises, you end up with an acoustic pabulum. “Dr. Ralf Kunkel adds:” We are all car-professionals, that is our great strength to the sound of experts from outside. We know our cars and we know exactly how they work and behave. ”

The e-sound from Audi is synthetic – but in an authentic way, and is regenerated every millisecond by the car itself, Dr. Lars Hinrichsen, an expert in the hardware and software, explains: “Our control unit receives information from the vehicle constantly over the speed of the electric machines, the load, speed and other parameters. From this data it generates the sound. ”

The e-bell sounds, a rugged speaker is mounted on the vehicle floor. Axel Brombach, the expert on this subject, says: “We have designed it to 40 watts of power, but in normal operation, we limit ourselves to five to eight watts. That’s enough to hear pedestrians and cyclists in the vicinity of the car. “By air-borne noise it is a small fraction of the sound in the interior. “On noise paths and mechanical actuators, can could recoup more sound,” says Dr. Kunkel, “a vehicle body makes a big orchestra.

But with our e-tron models, we attach great importance to the peace and quiet on board, because it conveys the special character of the electric driving is best. ”

Basic measurements: The acoustic test
Next scene: The acoustic test facility in the basement of the building is a large room of about 350 square meters and seven meters high. Meter-long wedges, filled with glass wool protrude from the walls close together. There they absorb a large part of the sound energy – the sounds sound almost like being outdoors. In the middle of the hall lies a chassis dynamometer, flanked by two long rows of microphones on stands. It is used primarily for passing noise measurements – the car is on the roll, the microphones are turned on.

Halbmeir and his colleagues have used this acoustic test bed for many of the basic steps used with the prototype of the R8 e-tron, which has e-sound technology installed. They also had the development of legislation to keep in mind – since the beginning of 2011 the volume of electrified vehicles regulations are promoted in the United States. “We will probably have to make up only 30 km / h sound, and beyond that the tire noise loud enough,” said Dr. Kunkel. “But that would be a little bit low, and we’ll be safe in a higher range.”

“The test for us was an important development tool,” says Axel Brombach. “But to really judge if the e-sound may be missing, we apply the real conditions of everyday life – the movement of wind, the sound of other cars. So we went on the road. See, hear, feel – that belongs together. ”

Out into the street, out of the building. Around the corner is a red Audi R8 e-tron rolling on, quietly, with a light hiss. But then Rudolf Halbmeir gently presses down on the right pedal, and the hissing becomes a refined growl, wrapped almost like a sleek V8, but clear, differentiated, with brighter, technical overtones: the Audi R8 e-tron sounds very competently like a sports cars, but very peculiar, very futuristic. Halbmeir stops and grins out of the window: “Well, that’s good”

The e-sound for the electric-powered high-performance sports car is just the beginning. Audi will give to all its future e-tron models an individual sound card – similar to one another, but always different. Because the sound of an Audi is much more than just noise: It is made of Vorsprung durch Technik.

Watch a video and hear the noise of Audi e-sound in a video posted in our discussion forum thread about this subject.

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