Electrical Driving and Noise

Update March, 11 2016: new legislation is upcoming, see also here. The United Nations’ World Forum for Harmonisation of Vehicle Regulations proposes this sound to be added artificially. To my opinion we should embrace that our world will become more silent, see also this blogpost of me from two years ago. In the past 81.000 km I did not run into any dangerous situation because my car was too silent.


soundRecently, the discussions about the absence of noise of electrical vehicles emerged because of upcoming legislation. The dutch TV came to our Automotive Lab, and made an item on this issue, see here for the link (Dutch). Here is a great blog “ZERO motorcycles: the sound of silence: quote “Think about noise and exhaust fumes from cars and motorbikes and scooters. We accept it, because we’ve never been exposed to a world without it.”

Already in 2008 Stanford University did some research into the subject.

In the USA a new law is proposed to have (always!) a sound below 18 m/h. From the LA Times:

“This proposal will help keep everyone using our nation’s streets and roadways safe, whether they are motorists, bicyclists or pedestrians,” U.S. Transportation Secretary Ray LaHood said in a statement. The Department of Transportation estimates the proposed changes to hybrid and electric vehicles would result in 2,800 fewer injuries to pedestrians and cyclists for every model year that such a system is required. The proposed noise would be necessary only at speeds under 18 miles per hour, the agency said. At 18 mph and above, vehicles naturally make enough sound to be detected. Automakers would have a range of choices for car noises, the agency said. The agency posted 14 samples of sounds at http://www.nhtsa.gov/SampleSounds.”


Now also in Europe the European Parliament has just mandated that electric and hybrid cars must add acoustic vehicle alerting systems by 2019/2021.

Based on my own experience I think this mandate should be handled with care. As an electric driver I would like to address the following remarks and concerns:

  • since an electric car is so quiet, we as drivers of electrical vehicles are also much more aware of our environment, and we act more cautiously than we would do with an ICE car,
  • not only e-cars hardly make noise at low speeds but also bikes, e-bikes, e-scooters, high class standard cars as Mercedes, BMW’s, Jaguar’s, Lexus, Toyota, etc. In fact, they all should then be forced into an acoustic vehicle alerting system,
  • noisein Europe alone, it is known we have about 3.000 people killed because of noise: it gives a higher adrenaline, and scientific research has proven this to be related to death. For this reason, the transition to electrical driving gives the ability in helping to drastically reduce background noise of traffic, and an alerting system could reduce this opportunity especially in cities!
  • we suggest to first give some room for further research to have either an active sensing system as additional requirement, or to have a system with the need for a driver’s action, like the bell on a bike (the system on a Twizy),
  • Guide dogwe should be careful for the problems of blind people. Because i got some emails from blind people, who were really concerned, i had the idea to require that every car broadcasts an electronic (non audible) signal, and an app on a phone or a small device that can be sensitive, for instance with a vibration. Then children, blind people, elderly etc can have such a small device, which starts to vibrate if (any!) cars comes too close. I applied for a patent, but the idea already existed.

I think we should have a discussion first before we add a constant noise to electrical vehicles, and instead be happy that the cities will become more quiet and healthy! Please give your comments below!

7 thoughts on “Electrical Driving and Noise

  1. I think that the fully electric cars should at least also have:
    – Smoke via an outlet of coal fired combustion. With ofcourse black color and appropriate odeur
    – Have an oil spill on the road
    – Should go every 10.000km to the garage to exchange spark plugs
    – Have hay on board to feed the horses that pulls the car
    – Should have a crank on front of the car to start the engine

  2. It is a good idea to alert pedestrians, cyclist and others about the presence of a vehicle. I experience the problem often in my Twike and in my Leaf, when driving on the touristic and country roads near my home. Although the Leaf makes some – very soft – noise at low speeds, the Twike makes no noise and the only solution is to turn-up the audio volume. With the horn as the least preferred option, but sometimes even unavoidable.

    However with all systems currently under development for sensing the nearby presence of cyclists and pedestrians, it should be possible to have by 2019 systems in cars, which produce noise only when and where needed.
    Therefore I think best would be if EU regulation would make the car industry responsible for developing and implementing a safe solution, that makes people aware of the presence of cars (and yes indeed not only for electric cars). And yes, for vehicles which have by 2019 not such a system, probably the only solution is to add noise.

    So in my opinion it is better to give the industry a clear assignment to solve the problem, instead of EU regulations with pre-scribed low-tech solutions which are for sure already outdated by 2019.
    By the way: 2019 and 2021 are far ahead: An intermediate solution for existing vehicles would not be a bad idea either.

    Harm Weken

  3. Another possible solution has been developed by Philips some years ago. Instead of electric cars making noise, this firm has developed an infrastructure which warns for approaching electric cars: the system consist of a kind of traffic lights (red, orange and green), that warn the pedestrians for possible danger. Philips has made some experiments on “Strijp-S” in Eindhoven, but it is unknown if they want to introduce the system.

    RIjkert Knoppers
    Science journalist

  4. Making cars more noisy is not safe but dangerous and unhealthy.

    I don’t have the references handy and it depends on how you measure it but I remember that background noise is an even larger health hazard (through increased stress) than fine particles (causing asthma and cancer). Both cause an order of magnitude more harm than traffic accidents (let alone traffic accidents to the blind).

    Unfortunately most people react to stories instead of statistics. Hence fear of terrorism while your own bathtub is more dangerous.

    Harm has an interesting point though with cars that only project noise when needed.

  5. Nice article and discussion.
    I agree on bullet point 3 that electric vehicles have the potential to reduce the noise level in urban areas, which should not be abated by a compilation of warning devices integrated in electric/hybrid vehicles. However, a differentiation should be made between functional sounds and noise.
    Since I work as an acoustic engineer for a Dutch OEM in the public transport industry, I would like to share some thoughts on public transport buses with respect to the noise issue.
    Compared to passenger cars, public transport buses face the same challenges with respect to noise, even when they are equipped with an ICE. Although the exterior noise level of a public transport bus exceeds the exterior noise level of most cars, the noise source is located 12 to 18 meters behind the windscreen. So the time you hear a bus (driving at low constant speed) might be rather late.
    With the introduction of the electric public transport bus the exterior noise level almost completely vanishes, which might result in unsafe situations as mentioned in the discussion. However, what surprisingly differs from electric cars is that the low interior noise level of an electric bus might be experienced as unpleasant, since having private conversations is no longer possible!
    My conclusion is that sound design, rather than conventional noise reduction, will play a bigger role in future (electric) vehicle development. It will be the perception of the sound characteristics of the vehicle, which defines the sound quality as good, acceptable or poor.

  6. Interessant stuk over of er wel of geen geluid door een elektrische auto gemaakt moet worden. De Tesla’s zijn voor mij een droom op wielen, voorlopig zal ik het met m’n Prius moeten doen (maximaal 2 km op stroom rijden). Wat ik een van de mooiste aspecten (na schoon en zuinig rijden) is juist die stilte (sound of silence). Qua veiligheid bemerkt ik zelf ook af en toe dat fietser of voetgangers m’n auto niet horen. Als er dan toch geluid gemaakt moet worden, componeer dan iets beters dan die blikkerige bromgeluidjes, pak een mooie V6, V8 of zelfs een V12 sound. Verder ben ik van mening dat het ‘tegenwoordig’ niets uitmaakt of en welke geluid je (elektrische) auto maakt aangezien half Nederland met oordopjes in of muzikale ‘oorwarmers’ op loopt of zich in het verkeer begeeft, zij horen niets anders dan hun eigen beats.
    Het laatste wat ik wil vragen /opmerken aan de heren op deze site met vnl.oer- Hollandse en ook Friese namen, waarom we niet gewoon in het Nederlands met elkaar communiceren of is Engels onze nieuwe voertaal geworden ?
    Met zonnige groet, Willem-Jan Hermans

    P.S. mocht iemand een oppas voor zijn / haar Tesla zoeken voor een week(end) of korte vakantie…….ik ben beschikbaar 😉

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