the industry battle to create the right noise, told from the inside

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The expectation of the silent car. The challenge that manufacturers will have to face in the coming years with the arrival of electric vehicle. Renault has opened its doors to us at Aubevoye, one of its French plants, to explain how it wants to add sound to its future models. The new automotive soundtrack is coming.

The facilities are an hour’s drive from Paris. There is a huge Renault test center with 620 hectares of extension and a thousand workers. Of these, 120 employees are dedicated to the department that studies, cares for and develops the acoustics in the new models. A job in which tests are carried out abroad, in the laboratory and even where the sounds and music that will accompany future electric cars are created.

“We are not prepared for silence”

With the proliferation of electric vehicles it was soon realized that we had a problem. Neither as drivers nor as pedestrians are we prepared for silence. In fact, the European Union has regulated this problem by establishing maximum and minimum noise limits that all cars must emit.

Of course, an electric car will never be fined by one of those noise radars that are already in operation in New York, but it does need to warn other pedestrians or cyclists that they are approaching, since not having a noisy engine like the one in a gasoline or a diesel increases the risk of being run over. Especially in the urban environment, where the rolling noise is really low. It is not just a question of looking up from the mobile phone or being more attentive. Take a visually impaired person, for example.

It is these sounds, the same ones that sometimes remind us so much of a spaceship, that alert pedestrians, cyclists and VMP users. But, curiously, these traffic agents are not the only ones who need a sound in the electric car. Engineers have to deal with a constant contradiction: the expectation of a silent electric vehicle and the need to create a sound to be heard inside the vehicle. At the same time, the quieter a car is, the greater the sense of quality and robustness of its materials.

From the brand they assure us that it is possible to create completely soundproof vehicles, where nothing is heard from the outside. Nor the sound of rolling or the one caused by the aerodynamics of the vehicle itself. Technically it is possible, although we assume that it is also too expensive. However, it is essential to have a noise that confirms that the engine is ready to be used. That the car is running.

It is a simple matter of auditory reinforcement of the sensations that we perceive with our eyes. If we accelerate without hearing a sound that is closely linked to it, a dissociation occurs in our senses that prevents us from being aware of the extent to which we are gaining speed. Renault, like other manufacturers, are forced to create a series of harmonies that accompany the next models.

Therefore, a balance game is produced in which unwanted noise sources must be eliminated, making the car the quietest vehicle possible and, at the same time, giving it its own personality in motion.

The soundtrack of electric cars

The Renault employees dedicated to the creation of the new soundtrack that will accompany the electric car not only have the task of putting on a constant background noise while the steering wheel and the throttle. The work is much more complex, fine and extensive.

During the demonstrations of the sound team, we were able to check the bases on which Renault is working. Thus, in future models you can choose three types of tones. The first of them is certainly metallic and reminds of a spaceship. Or, at least, how we imagine a spaceship should sound. Damn cinema. In contrast, you can choose a sportier tone, which raises the volume and is more sensitive to changes in the accelerator pedal.

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Finally, the most complex, which during the demonstration was called Ambience. In this tone, numerous natural noise sources that harmonize to create a more relaxed space in the cabin. According to the brand’s own engineers, it is more complicated to simulate this environment than to give an electric car a certain sporty air, since many more variables are involved here that must be harmonized to give it its own personality.

This time, changes in throttle were accompanied by changes in pace, faster as the vehicle moves faster. Lifting the foot of the Renault Zoe and activating regenerative braking caused an automatic relaxation of the tones, although always in very fluid transitions that did not break the experience.

The same thing happens outside. Up to three different shades alert pedestrians and other agents on the road that a Renault Mégane E-Tech is approaching. In this case the tones were divided into Expressive, Neutral and Pure. Personally, I noticed less difference here, but it may be due to my own hearing. It was never the finest.

What is clear is that, with the electric car, each sound emitted inside and outside the car, what we have called here “its soundtrack”, will be a new fundamental and distinctive part of each vehicle. A defining feature that takes into account the aesthetics of the vehicle and that will allow us to know which vehicle is behind us without having to turn our neck to see it.

Much more than a melody

But, as we told you, creating a new melody for the advancement of new electric cars is not the only thing Renault engineers are dedicated to. Sound is a fundamental part when it comes to create your own environment inside the car, to provide it with its own recognizable identity for any user.

From the welcome announcement to each and every car alert. Everything has to have harmony and meaning. “If I let them, I could create more than 100 alerts for all the requests I have”, assured us one of the engineers, in charge of controlling what sounds and what does not in the car, what is so important that its activation disturbs our driving . “In each model there are between seven and ten types of alerts that, in total, reach about 30 variations in which the volume and the time in which they are active intervene. We would go crazy”, he summarized for us.


But the sound in a car is not only how it sounds, but also where it sounds. With a recorder they showed us that the room we were in could perfectly be a recording studio that simulated the passenger compartment of a vehicle. With it they can collect sounds and simulate 3D spaces that, in the future, they hope to be able to replicate in their next models. Ideally, each passenger should be able to personalize your experience sound without needing headphones for it. It would be a huge leap forward to enjoy the average three hours we spend listening to music, podcast or radio. According to Renault, half of this listening time is spent in the car.

A spatial experience is what speakers already offer harman kardon of the new Renault Mégane E-Tech. Its equalization allowed us to verify the sound offer offered to the driver and passengers. With its “Studio” mode you can know where each instrument is, through its eight speakers, its subwoofer and its amplifier. If the “Concert” mode is selected, it gives the feeling that all the sound will come from the front area, the “Club” reinforces the bass, for example.

What’s more, Stephane Barrelet, head of the Renault Group Acoustic and Vibration Service, also stressed the importance of placing each sound source in the right place. “It doesn’t make sense for the singer’s voice to sound at our feet, we have to raise it to the position of the conductors’ heads. Therefore, when we select the ‘Immersion’ mode, the sound reaches us at the same time from all places, we are the center of everything, as if we were part of the band”, he stressed.

The semi-echoic chamber: where outside is inside

To achieve all this, Renault has the Aubevoye facilities, a place with more than 60 kilometers of test tracks, 33 “out of the ordinary” tracks, where the sound emitted by each vehicle is tested in different conditions: high and low speed, different types of pavement and tires, rain, dry… A space that is accompanied by 44 test benches and 75,000 m² of roofed facilities. It is the dream of any crazy engineer. Whatever.

As far as sound is concerned, the firm’s employees collect tests under numerous conditions which they then try to simulate in the semi-echoic chamber. There is one of the great curiosities in the chain of work developed by Renault: we feel outside the car what would be heard inside it. Let’s explain ourselves.

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First, all the noises emitted by the vehicle when driving are collected, as we have said, in different and numerous situations. “We literally have terabytes and terabytes of data collected,” he explains. Louis-Ferdinand Pardo, Specialist in Acoustics Life on Board. With numerous microphones, they even pick up the noise that a vehicle faces when it is overtaken or when it has a truck or bus behind it.

The car is then placed in the semi-echoic chamber. A place completely isolated from the noise of the plant and where the walls absorb all sounds, eliminating reverberations. It is about simulating that the vehicle is outside and that it does not have walls on the sides. In silence, inside, 20 decibels of white noise are perceived. The same as in a recording studio. Only the floor lacks the insulating material, since it will always be rolling on the road.

The noise picked up is emitted inside the vehicle through a probe, with the doors closed. Outside, we barely heard anything. This barely perceptible noise is what we would feel if we moved in the specific conditions in which the sample was collected. That is, at the foot of the car, next to its door, we feel exactly the same as if we were inside.


The car is surrounded by a good number of microphones (up to 125 devices can be installed) that pick up the noise that comes from inside the car with all its doors closed. The perceived decibels will be the same as what passengers will hear when using the Renault Mégane E-Tech that is being tested. In an adjoining room, the engineers analyze what sounds and where, to understand what they need to improve on the isolation. According to the brand, the electric compact is 50% quieter than its combustion siblings.

We left Aubevoye overwhelmed for the amount of resources, time and money that is spent on each and every one of the details of any car that is launched on the market. It is a feeling that repeats itself whenever I have the opportunity to visit a brand’s facilities. Of course, it is clear to us that what until now we perceived as noise will soon be silence. And that silence will become an individual harmony for each vehicle.

The expectation of the silent car. The challenge that manufacturers will have to face in the coming years with the…

The expectation of the silent car. The challenge that manufacturers will have to face in the coming years with the…

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