1.10.4 - Noise and urban electric vehicles

Version 5


    As we know Electric Vehicles (EVs) are noiseless (< 10 decibels). Thus they are particularly well adapted to an urban use. Two other reasons are their lack of emissions and their smaller footprints when they have been designed as an EV.


    A number of metropolitan areas have launched master plans and investment programs to foster the use of these small “green” vehicles in two main domains:


    • Incorporating more electric vehicles into city fleets: the city of Shenzhen, China recently acquired 1,500 electric vehicles which bring its EV fleet to around 2,000, the largest in the world. In large Chinese cities, the development of electric vehicles is a major priority for reducing atmospheric and noise pollution.
    • Implementing logistics platforms on the outskirts of the cities to direct the flow of thermal delivery vehicles to these platforms and then use electric utility vehicles for the remaining kilometer(s). Many cities worldwide are implementing such platforms.


    Electric delivery vehicles and fleets of small electric models are currently making the biggest contribution to reducing urban noise pollution.


    Sound signature


    Beyond noise reduction, vibration-acoustic engineers are now also working on the car sound signature: by using the engine and exhaust pipes as musical instruments, they create an acoustic identity which corresponds to a particular car range or brand (power, safety, sportiness, etc.). For example, the PSA group has a “New Sound lab” working on filtering and isolating certain frequencies using an on-board software program to produce "sound colors" that are pleasing to the ear. 


    As a result of new traffic regulations, electric cars are also starting to make use of sound design. In this case the goal is not to reduce noise, but rather to create artificial sounds so that pedestrians and other road users can hear approaching electric vehicles. In a recent study, the National Highway Traffic Safety Association (NHTSA), the American government agency in charge of road safety, estimated that adding sounds to electric vehicles would prevent 35 deaths and 2,800 injuries per year in the US. In the wake of this study, the NHTSA proposed regulations to require quiet cars to make artificial sounds below a certain speed.


    Similarly, on February 6, 2013, the European Parliament adopted a bill to reduce the noise level of gasoline or diesel cars, and require acoustic warning systems on electric cars. This bill should take effect in 2019.


    However car manufacturers are already adding sounds to their electric models, in advance of these regulations. The Renault Zoe is equipped with a sound system called "Z.E Voice," which gives drivers a choice of 3 different sounds to warn pedestrians and other road users. Audi is also leading the way on the issue, with the creation of futuristic synthetic sounds that will be integrated into its e-tron electric models.