Topic Acoustics and Sound Systems at Audi TechTalks

Audi sound philosophy is to bring acoustic harmony to the car.
Audi sound philosophy is to bring acoustic harmony to the car.

Seeing sound and acoustics as much more than the quality of infotainment, Audi strives to create a holistic and natural sound that is best adapted for each model: At Audi, the sound of the audio system is among the fundamental qualities of quality.

Customers who want to be in an exciting and inspiring environment inside their cars are also extremely sensitive to sound. He wants an acoustic space where the background sound is not distorted and that contains signals, warnings and information that are harmoniously compatible with each other and inconspicuous activation sounds.

So what sounds do people perceive in the car and where do these sounds come from?

This subject was discussed in a new technology meeting organized by Audi under the name of TechTalks events.

Sonic background in an automobile consists of a mixture of a wide range of noise and sounds. Such as the engine noise, the usual driving noises caused by the rotation of the tires on the road, and the aeroacoustic noises caused by the air flow in the chassis while the car is in motion. There are acoustic feedback sounds such as window automatics that make a little noise, door closing sound, warning, signal and information sounds, functional messages.

Audi detects unwanted noise sources with Rustle and Rumble team

Audi handles the issue of reducing noise inside the vehicle holistically. The Rustle and Rumble team are working together to this end, consisting of experts in the fields of car design, chassis development and quality assurance.

These experts test and evaluate each new Audi model with special devices and hydropulse equipment that provide the appropriate environment for different road and vibration conditions. This special device, a servohydraulic four-point test stand that vibrates the car, serves to investigate and detect disturbing noises such as clicks and squeaks caused by vibrations at frequencies as low as 50 Hertz in the passenger compartment. Testing for individual components or the entire chassis for vibration responses.

Are there acoustic differences between internal combustion engines and electric cars

An electric motor causes almost no oscillation, vibration or mechanical noise, unlike an internal combustion engine. In such an environment, previously imperceptible sounds may come to the fore. This includes the noise the tires make when rolling on the road.

Audi is making great efforts to minimize all these disturbing effects as soon as they occur. For example, in the chassis of the Audi e-tron, all areas where an annoying noise can be transmitted are specially isolated and segregated. In other words, the design-related openings and gaps in the case are filled with microfiber material. The floor is covered with a special material. On the front, the complicated multi-layer insulation row prevents the noise from passing into the interior from the front. A similar structure is located at the back. The electric motors are encased in noise-reducing capsules. Even the under floor covering is designed to absorb sound. Foam-backed carpet coverings in the interior maintain silence.

Generally, wind noise becomes very pronounced when a car reaches speeds of 85 km / h or more. This noise remains at a very low level in the Audi e-tron and hardly ever penetrates into the interior thanks to the intensive fine tuning of the door tires, exterior mirrors and waterstop strips. Passengers can comfortably even at high speeds. sohbet can. The windshield of the car has double glazing as standard. Audi is optionally available with acoustic glass for the side windows.

Raising or actively avoiding sounds in the car

Active acoustic measures have become even more important in recent years. For example, a certain part of the engine noise can be reduced with active noise cancellation (ANC). Based on ANC microphones placed in the roof lining and measuring the sound level indoors, a controller reverses disturbing sound waves and saves neutralizing sound through the subwoofer. However, actuators are also used in the exhaust system to emphasize the desired sounds. Powerful speakers ensure that the engine sound has a dynamic effect as desired.

How to experience a pleasant and non-disturbing atmosphere in a car: 3D sound

Sound enhancers come into play here. They take care of all the sounds and, if necessary, adjust, suppress or accentuate them to ensure that each sound contributes to the acoustic harmony in the car.

In addition to having many noise sources, cars also have particular challenges with regard to an acoustic field: the number of passengers sitting in different positions, the number of people inside, whether they have a panoramic roof, whether they have fabric or leather coverings, and above all, the time it takes for sounds to travel from the speakers to the listeners' ears …

The term 3D sound defines a sound that reflects acoustically all three dimensions of a space. When sound recording was invented, sound was reproduced through a single speaker - mono. In the 1960s, three-dimensional sound began to be widely accepted: two microphones recorded music from different locations, and when it was played back, the recorded music was allocated to two different channels. Thus, a spatial sense of sound, stereo effect has been produced. The term "1-D" refers to this, that is, stereo sound.

Accordingly, "2-D" stands for surround sound: This multi-channel technology has been used since roughly the turn of the millennium. Music comes from a subwoofer and a few speakers from the front, back and sides - like 5.1 and 8.1, depending on the number of speakers. At this level, each sound effect is assigned to only one speaker or only a specific speaker group.

In order to obtain 3D sound, an additional sound source that is not at the same level is required. In the new generation of the current Q2016 model, which Audi introduced in 7, it presented Bang & Olufsen sound systems with 3D sound. Thus, the interior turns into a big stage that gives the music the feeling of being recorded in the hall. There is an algorithm behind this technology developed by Audi with the Fraunhofer Institute. Symphoria 2.0 3D algorithm calculates the information from stereo or 5.1 recordings for 3D and processes it for 3D speakers. In this sense, Audi uses Bang & Olufsen sound systems, which include a digital signal processor, a powerful 23 Watt amplifier with 24 channels with 1.920 speakers, at the highest configuration level in large class models.

Audi does not compromise on sound quality in the compact class, either. On the contrary, it adapts the technical concept to the spatial conditions. The A1 model, for example, has four mid-range speakers that are directed vertically up the windscreen and use the windshield as a reflective surface. In this way, high quality 3D sound can be obtained even in a compact class car.

Digitization and sound arrival

Audi significantly reduces the version variety and related development time with the soundCUBE audio software solution it has developed. Audi is also virtually improving new sound solutions in its ultra-modern digital sound lab. Using lifelike simulations, experts tweak the audio settings for various series even before a prototype emerges. This makes it possible to analyze the sound configuration of each seat in the virtual reference room to provide the best possible personal listening experience for each passenger at their most efficient point.

The next big innovation

Audi's sound experts are currently working hard in the sound lab on the holistic sound experience of tomorrow. Immersive 3D is at the center of the work. With traditional 3D surround sound, sounds are assigned to specific speakers according to certain algorithms. Unlike this channel oriented system, immersive 3D audio is object oriented. In such a process, the sounds in the audio files are already linked to metadata, which is a perfect reflection of the acoustic state during recording, containing precise information about how and where the corresponding sound should be heard in the real space. Immersive audio is at the center of all-new entertainment experiences that impress all the senses. But in the future, people in an auto-driven car will have all their senses to fully enjoy such a sound experience when they can stop dedicating themselves to the driving task.

The next big innovation: the future deployment of the 5G high-speed mobile communications standard, new, high-quality. Until now, many people have used their smartphones in the automobile as the primary receiver for audio streaming services. Using Bluetooth, the recordings on the phone were easily transferred to the car. However, because the bandwidth for Bluetooth wireless technology is limited, it sometimes causes a loss of sound quality. In the near future, Audi plans to use the car itself as a receiver for the first time, via the built-in SIM card and a high-performance receiver module for true multi-channel audio streaming. This is seen as another milestone for Audi sound engineers on the road to the future.

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