It concerns their sound – or rather, the lack thereof – and rival schools have emerged. The first argues that EVs should remain quiet, void of any added sound. The second believes that these vehicles pose a risk to pedestrians and cyclists because they may creep up, ostensibly unannounced by a gurgling engine.

Recently, however, a small group of musicians, car designers and technicians have come together to create sounds for electric-powered vehicles that not only communicate, but harmonise with their environment. 

Sonic Movement is a project born out of the Research and Innovation Lab at Semcon, a Sweden-based engineering and technology services company. Using September’s Frankfurt motor show  as its springboard, the team presented their idea to use pre-rerecorded and gathered sound elements to communicate an EV’saction. James Brooks, one of Sonic Movement’s principals, says that an EV’s sound "shouldn't be too complex; it should be almost second nature when you hear it".

In Sonic Movement’s vision, sensors and microphones would be fitted to EVs, which would capture sounds from the vehicle's environment and manipulate them using onboard filters and synthesizers, with the “composed” sound being piped out through speakers mounted outside of the vehicle.

The sound-engineering experience begins at an EV’s idle. This, the group calls a “core” sound, which would theoretically stand in for – but not try to replicate the sound of – an internal combustion engine at idle. The designers have also devised sounds for turning, acceleration and deceleration, which would be modulated to suit the conditions of the moment.

Some of the pre-recorded elements originate with Holly Herndon, a musician who became involved in the project shortly after Brooks listened to her conceptual recording inspired by sounds Herndon heard in her car. For her part, Herndon wanted to ensure that the sounds she created for the project were not "completely foreign to people, but that it had a new aesthetic".

The practical objective of Sonic Movement is to create a soundscape that would alert pedestrians and cyclists of an EV in their midst. But Sonic Movement’s creators also see a degree of salesmanship involved. Creative director Fernando Ocaña notes that car stylists spend years working on a design, in the hopes that the vehicle will communicate the values of the automaker. Designing distinct automotive sounds "opens a whole new channel for brands to communicate those values", Ocaña says.

Automakers and legislators worldwide have vexed over the question of battery-electric and hybrid vehicles’ relative silence. Ocaña notes that legislators were "looking at this from a technical point of view, whereas we're looking at it from a user experience point of view". And by giving EVs symphonic qualities, the question is no longer whether EVs should make sounds at all, but whether the sounds they make can “sound good”.

Next steps are to put the theory – and Herndon’s recorded soundscapes – on the road. The group hopes to gain interest from the automotive industry as it prototypes the sound equipment. The powertrains of EVs and hybrids will continue to evolve; the avenues for acoustic design could very well grow in step.