Audi created a specific sound it is naming “e-sound” to create awareness in the surroundings of its A8 e-tron model.

The challenge is one many electric cars face. Audi had to make sure pedestrians would hear and notice the presence of the electric A8 close to them.

Audi’s goals for this e-sound was to make sure it would sound like a sports car, but also, a one-of-a-kind and very futuristic sports car.

The e-tron generates its sound by the millisecond using data relating to the electric motor’s rotational speed, vehicle speed, loads, and other parameters. The e-tron then uses this data to generate sound.

A sturdy 40-watt loudspeaker attached to the car’s undercarriage plays the e-sound.

As the vehicle accelerates, the purr turns into a cultivated growl and is inspired by the sound of the company’s V8 engine.

The e-sound was developed in a giant acoustic test bed, a large room used as a laboratory with dense rows of wedges full of glass wool, each three foot in length, projecting from the walls. These wedges absorbed a majority of any sound energy, allowing things to sound almost like they do outdoors.