The science of sound

What emanates from the speakers within the new Audi A6 e-tron's interior may not sound like music at first. It's more about pure sound. A peculiar hum reminiscent of science fiction. "You can scratch the fiction part," says Philip Sedlmeir, an Audi sound engineer, "but it definitely has a lot to do with science." These ‘sweeps’ are acoustic signals used to detect unwanted noises when the sound system is active. This could be a rattling speaker grille or a poorly routed cable causing interference when a speaker is engaged. Such occurrences are rare during the development process and, thanks to the specialists at the Audi Sound Lab, never make it to the final product. 

However, the initial stages of this process are not about what you hear, but rather about functionality. 

"We typically start with the speaker layout, determining where each speaker will be placed in the vehicle," explains Jörg Kotschak, Sedlmeir's colleague and a member of the Audi sound engineering team for the past four years. He is part of the team that defines the performance parameters of each speaker, measured not in watts but in functionality. 

This can include music playback, telephony, and navigation announcements. Kotschak also outlines what should happen when customers adjust settings, which in the new Audi A6 e-tron, the front passenger can do individually using the new Passenger Display. 

"We meticulously define the system's capabilities and specify the requirements. This culminates in components, control units, software, and algorithms." 

In the case of the new all-electric Audi A6 e-tron, up to 20 speakers – including the optional Bang & Olufsen Premium Sound System with 3D sound and headrest speakers – need to harmonise perfectly. Kotschak is particularly proud of four of these speakers, two of which are integrated into each of the front headrests to create the ‘Sound Zone’. 

"We didn't just integrate any speakers that can reproduce sound into the front headrests. That wouldn't be a premium solution in the Audi sense," he explains. In the new Audi A6 e-tron, the Sound Zone enables specific functions such as personal surround sound, navigation announcements and personal telephony, all individually adjustable for each user. For example, the driver can focus on navigation instructions while the passenger enjoys an undisturbed phone call. 

"Everything is fully integrated into the sound system, and to this extent, it's unique in the market, in my opinion." Only when Jörg Kotschak is convinced that each component can deliver on its promise does Philip Sedlmeir step in.To achieve the best possible acoustic experience inside a new Audi model like the A6 e-tron, Sedlmeir and his colleagues are involved right from the project's inception.

"About six months before production starts, a vehicle like the Audi A6 e-tron arrives at my station for tuning. That's when the real fine-tuning begins," says Sedlmeir. The electrical and information technology engineer spends countless hours in the vehicle, listening to music and analysing data. Equally demanding is the co-ordination of up to five different companies and departments involved in tuning the A6 e-tron's sound systems. These include specialists from Bang & Olufsen and sound engineers from the Fraunhofer Institute for Integrated Circuits IIS. Their expertise and specialised algorithms ensure that in the Audi A6 e-tron listening to music transforms into an immersive experience. 

"I'm constantly listening, providing feedback and making sure that everything ultimately sounds the way we envision it at Audi.”

This distinct ‘Audi Sound’ can be visualised through curves and graphs on large screens or summarised ins this way – It should sound premium, meaning the highs must be reproduced with utmost precision and the bass delivered with a crisp punch. 

"They say you hear the high notes with your ears and the low notes with your stomach and heart. This means we aim for precision and emotion," explains Sedlmeir. In the best-case scenario, he describes the desired outcome as rediscovering your favourite song entirely. Achieving this level of quality requires three to four months of meticulous fine-tuning.

Naturally, the Audi sound engineers fine-tune each model and equipment variant individually. 

"The Audi A6 e-tron's subwoofer is installed in the boot, but the Avant has a completely different boot layout compared to the Sportback. Insulation, surfaces and volume all play a role and we have to take that into account," explains Kotschak. 

"Two models of the Audi A6 e-tron, each with three selectable sound systems, result in six tuning runs. Multiplied by two, considering right-hand and left-hand drive variants, we end up with a total of 12 tuning processes.”

Once the static measurements are completed in the sound lab, the team takes the vehicles to gravel roads, highways and racetracks to incorporate the various soundscapes encountered during real-world driving into the settings. 

"The system dynamically adapts to the noise level," says Sedlmeir. It's a meticulous process, but one that both sound engineers believe is well worth the effort. They claim they could pick out an Audi-tuned sound system from any selection of vehicles due to its distinctive sound signature.

The final test – instead of a hum, a classic rock song now emanates from the speakers of the Audi A6 e-tron. 

"This is one of my reference tracks," says Sedlmeir. "It offers a wonderful range of tones and sounds. If it sounds right, we've done a lot right." 

"The Audi A6 e-tron provides the ideal setting for truly experiencing this level of audio quality,” Jörg Kotschak adds. “Especially the optional Bang & Olufsen high-end system makes it possible to discover musical fragments and subtle details often missed otherwise.”

But is this the perfect acoustic experience? Music, both Audi engineers agree, is pure emotion and a highly subjective matter. 

"Subjectively perfect is a contradiction in itself. Our goal is for you to want to listen to at least one more song in the car, even when you've already arrived at your destination.”