The Sound of Silence in an EV

With no engine noise, why do electric vehicles need special consideration for their stereos?

It sounds like the start of a joke from a stand-up comedian: did you hear the one about the electric car that was too quiet?

But car manufacturers and their stereo suppliers certainly aren’t laughing with the new technical aural challenges that EVs bring.

It’s stating the obvious, but electric cars don’t have a combustion engine under the bonnet. Therefore, you’d imagine because of that, compared to a petrol or diesel car, it should be a lot easier to develop a stereo for them, right? Wrong. The new all-electric Kia EV9 which arrives into showrooms this spring will feature one of the first sound systems developed specifically for the unique audio characteristics of a pure electric car.

Developed by British firm Meridian, the EV9’s stereo is a new 14-speaker sound system that uses a number of digital technologies optimised for the challenging acoustic environment of an electric car. The idea of a car that produces no noise being a ‘challenging’ environment for a car stereo may sound a little strange, but it’s to do with the type of noise rather than the level of it.

“The challenge with producing a fantastic audio experience in an EV isn’t the level of the background noise, it’s the complexity of noise sources and their frequency profiles,” said John Buchanan, Meridian Audio chief executive. “These are typically at significantly higher frequencies than in a combustion vehicle, which can affect our ability to perceive the position of sounds and they can be more random, which makes the acoustic environmental more difficult to manage with active noise cancellation.”

In short, the noises that the engines in a traditional petrol or diesel car make are more consistent and easier to manage than those in an EV. The firing of an internal combustion engine is at a lower frequency and therefore manufacturers can use active noise cancellation to balance that out. The new Range Rover even uses active noise cancellation through its headrests.

By comparison, while an electric car might not have an engine to cancel the noise from, those higher frequencies in an EV mentioned by John Buchanan are significantly harder for a stereo manufacturer to deal with. Moreover, those higher frequencies can also interfere with the quality of surround sound in an EV – almost like the difference between listening to something in mono or stereo.

Which is where all the hard work from Meridian comes in. By switching their focus from the hardware to software, Meridian’s engineers were able to manage the acoustic environment through processing their software to tailor the sound. Put simply, in years gone by, they would tailor the sound of a car stereo using special speakers and their location within the car, while now they’re able to do that electronically.

And, while this technology has only just been fitted to the new Kia EV9, inevitably similar tech will trickle down to more electric vehicles over the course of time which will gain similar stereo systems. We can’t wait.

The first deliveries of the new Kia EV9 take place this spring with prices starting from £73,245.