Usually we notice the sound our car makes only when it’s the wrong kind. But car sounds are becoming more important for electric vehicles because we simply don’t hear them. This means manufacturers are spending millions to create just the right sound to fit their brand.
The meaning of sound
The sound of a car has essentially two meanings – functional and aesthetic.
An example of function is where sound alerts us to how the vehicle works, such as when to change gear. Aesthetics are not useful but a characteristic of the vehicle, for example, sophistication or smoothness. If you’re a Harley rider, it’s that unmistakeable loud growl.
Another functional purpose of car sounds is to alert pedestrians to look out for a vehicle. This is the main problem EVs pose when travelling at low speeds.
They are 40% more likely to hit a pedestrian than other types of vehicle. People with poor eyesight, children or just people not paying attention, fail to hear them coming. Monash University Accident Research Centre found pedestrians are colliding with EVs, most often on pedestrian crossings (16%) and on footpaths near driveways (24%).
Laws for sound
For this reason, the EU and the US have mandated that EVs make a sound at low speeds.
All electric and hybrid models in Europe, from July 2019 must make a noise at low speeds. Current models will be retrofitted. US electric vehicles must by September 2020 make sounds at low speeds. Meanwhile, Australia’s Infrastructure Department has no plans to introduce such a law.
Perhaps it is because so few people are driving EVs. But surely this will change and it is better to fit new vehicles than have to retrofit them later.
What sounds do we like?
Apparently older people get emotionally attached to the car sounds they were used to hearing as they grew up. This means designers aim to appeal to their market by choosing those emotional sounds. However, younger people buying EVs have less idea of how a car “ought” to sound. For these buyers, the sound will be less constrained by history.
Future vehicles are likely to use a mixture of tonal and broadband sounds.
Broadband sound, or white noise, uses a wide range of frequencies at once, such as the roar of the ocean or distant traffic. We are less annoyed by this type of sound and it is easy to tell the source of it.
A tonal sound is obvious, such as the “beep beep” of a reversing truck, but bounces off hard surfaces making it harder to locate the source.
Design a sound
Imagine you have to design a noise for your next vehicle. Let us know what it might sound like. (Definitely no leaf blowing or hedge trimming noises.)