Lucid Motors is Working on an Anti-Noise Signal for Its Electric Car

Matt Posky
by Matt Posky
lucid motors is working on an anti noise signal for its electric car

One of the first things you notice in the silence of an electric car is how prevalent wind and tire noise can be without an internal combustion engine to breakup the aural monotony. While no one has ever slipped into madness due to an overabundance of road noise, rubber grinding against concrete at seventy-five miles an hour isn’t the most pleasant sound in the world, either.

Lucid Motors promised that its upcoming Air EV would possess an audio system equipped with active noise cancellation to ensure that its interior remains a silent space. However, we are only just now discovering how seriously they took that promise.

The vehicle’s 29-speaker audio system can devote up to eleven speakers to noise cancellation using “anti-noise,” while the car itself takes advantage of acoustic laminated glass and other sound dampening materials. Lucid claims it has modeled the software for varying road surfaces, realizing that roads in North America typically use coarser variations of asphalt than those smooth Europeans.

According to the company, the anti-noise signal piped in through those eleven speakers can create quiet zones for the vehicle’s occupants and is endlessly adaptive. Lucid says the system requires an previously unheard of number of sensors, several digital signal processors, software developed specifically for broadband noise, and careful integration into the vehicle’s audio system to function properly.

That’s a lot of effort for something that, when working, is completely imperceptible to the human ear.

However, Lucid says it is those little indiscernible features that separate a quality product from a lesser one. Devoting an entire engineering team to “ Noise and Vibration Harmony” is, apparently, par for the course when you’re trying to raise the bar.

While it would be easy — and predictable — for a skeptic like myself to attribute this entire thing to one big fat marketing gimmick, active-noise-cancellation technology has advanced in leaps and bounds in the 21st century. Texas Instruments even has a particularly comprehensive report on the subjec t that I wasted an hour of my life reading through.

While steady droning sounds are easy to eliminate, sounds that are variable and unstructured (like road noise) are much more difficult to counter. Thus the need for the Air’s sensor array, specialized software, and multiple processors devoted specifically to developing ambient sounds to counter noise created by air or pavement.

In addition to the computerized adaptive anti-noise, Lucid has done loads of digital modeling to tweak the car’s aerodynamics and suspension to reduce sound — even altering the vehicle’s shape to encourage less of an unpleasant din. The company says that feature, in addition to large-scale usage of sound-dampening material and interior acoustics, should make the Air’s cabin one of the quietest in existence.

[Images: Lucid Motors]

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  • VoGo VoGo on Feb 02, 2017

    I am heartened to see that a fantasy vehicle that will never be produced can run so silently.

  • THX1136 THX1136 on Feb 02, 2017

    With the way things in the digital audio world I am somewhat surprised that this has taken so long to appear. In Pro Tools - and other DAWs - one can take an two tracks of audio (same instrument from 2 different mics), throw one 180 degrees out of phase and the only thing left is the differences between the two. Same thing for this application; 11 mics measuring interior noise at the specific locations of the speakers used for the noise cancellation; use real time digital processors to invert the polarity of the sampled noise and Wah-Lah - reduced interior noise in those 11 specific areas as it is cancelled out.

    • See 2 previous
    • Mriach77 Mriach77 on Feb 03, 2017

      @JimZ Hi TTAC, Long time reader—first time posting. As a recording engineer 20 years into my career, and an instructor on the topic in my 13th year—I can imagine how this would work. A basic understanding of superposition will help to understand i.e. the summed interference between two identical sources cancelling when, one source being phase shifted by any degree—the most extreme shift being 180° out of phase, specifically "out of polarity" yielding dead silence. This is certainly not a new concept, frankly the more one chisels away at the nature of physical law—the more one realizes everything i.e. matter, can be reduced to energy—heat—information— it whatever you's a a wave of probability...just like sound, music, noise, again; whatever you want to call it. So I assume the principal here will be the same—chiefly, because a car's interior acoustics do not get a new set of laws. Nature works the same in a Trabant, as it does in a Studio. Now that I think about it—the Trabant may have less sound transference, but my point: the laws of nature don't change here. Broadband noise reduction In a car could possibly be employed by placing omni-directional microphones around the car's exterior, perhaps with a realtime filter that processes the incoming input signal in a way that matches what the natural acoustic noise sounds heard in the car which is influenced by the construction of the vehicle. In this hypothetical build, the live filtered feed of "matching" noise from the outside world is amplified to match the volume of the acoustic noise. The result: same or very nearly similar frequency response, as well as volume...actually it's SPL but I digress. Now that interior has the same acoustic noise inside, as the incoming processed signal, using DSP to flip the polarity on the processed signal will cancel out anything that was exactly the same. The harmonic content will be complex, so in this method—absolute silence will be difficult, but noticeable attenuation is certainly possible. Cheers! -Michael

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