Electric vehicle warning sounds
In 2007 research at the Technical University Munich showed that ordinary vehicles in background noise are often detected too late for safe accident avoidance.
[10][11] Research conducted at the University of California, Riverside in 2008 found that hybrid cars are so quiet when operating in electric mode (EV mode) that they may pose a risk to pedestrians and cyclists, especially the blind, children and the elderly, as they may have only one or two seconds, depending on the context, to audibly detect the location of approaching hybrid cars when the vehicles operate at very slow speeds.
[12][13] The experiment consisted of making audio recordings of a Toyota Prius and combustion engine Honda Accord approaching from two directions at 5 miles per hour (8.0 km/h) to ensure that the hybrid car operated only with its electric motor.
In a second trial, the background sounds of two quietly idling combustion engine cars were added to the recordings to simulate the noise of a parking lot.
[12][13] A separate 2008 study from Western Michigan University found that hybrids and conventional vehicles are equally safe when travelling more than about 20 miles per hour (32 km/h), because tire and wind noise generate most of the audible cues at those speeds.
Similarly, The NHTSA study also concluded that the incidence rate of bicyclist crashes involving HEVs for the same kind of manoeuvres was significantly higher when compared to conventional vehicles.
[14][15] Among other findings, before the trial drivers participating in the field testing were concerned about being a danger to pedestrians and cyclists due to the quietness of the electric-drive vehicle.
The goal is to present recommendations to manufacturers for a system to be installed in vehicles to provide an audible signal to pedestrians and vulnerable road users.
This interim guideline is intended to provide guidance until the completion of on-going research activities and the development of globally harmonised device performance specifications.
[19] On 6 February 2013, the European Parliament approved a draft law to tighten noise limits for cars to protect public health, and also to add alerting sounds to ensure the audibility of hybrid and electric vehicles to improve the safety of vulnerable road users in urban areas, such as blind, visually and auditorily challenged pedestrians, cyclists and children.
The draft legislation states a number of tests, standards and measures that must first be developed for acoustic vehicle alerting systems (AVAS) to be compulsory in the future.
A previous study did not find an increased pedestrian accident rate for electric and hybrid vehicles with respect to their conventional counterparts, which raised the question as to whether added sound is necessarily required.
[25] UK organisation The Guide Dogs for the Blind Association lobbied members of the European Parliament to vote in favour of legislation to make the installation of artificial sound generators mandatory on quiet electric and hybrid vehicles.
The NHTSA estimates that the new warning noises would prevent 2,800 pedestrian and cyclist injuries during the life of each model year electric and hybrid vehicle.
Some automakers also said there is no need for electric-drive vehicles to play sounds while not in motion, "since it is not clear that it helps pedestrians to hear cars that are stopped in traffic or parked."
[3] Enhanced Vehicle Acoustics (EVA), a company based in Silicon Valley, California and founded by two Stanford students with the help of seed money from the National Federation of the Blind, developed an after market technology called "Vehicular Operations Sound Emitting Systems" (VOSES).
[39][40] VOSES uses miniature, all-weather audio speakers that are placed on the hybrid's wheel wells and emit specific sounds based on the direction the car is moving in order to minimize noise pollution and to maximize acoustic information for pedestrians.
[39] The company argues that "chirps, beeps and alarms are more distracting than useful", and that the best sounds for alerting pedestrians are car-like, such as "the soft purr of an engine or the slow roll of tires across pavement.
According to the company, its technology sends audible signals only in the direction of travel, thus allowing the vehicle to be heard by those who may be in the car's path, without disturbing others with unwelcome noise.
[48] However, ultimately Ford decided to hold off including warning sounds unless federal legislation required it, and no such system was implemented on the production vehicle.
[49] General Motors' first commercially available plug-in hybrid electric vehicle, the Chevrolet Volt, introduced in December 2010, includes warning sounds for pedestrians.
[53][54][55] The automaker conducted a test with a group of the visually challenged at Milford Proving Grounds in order to evaluate the audible warning systems on the Volt when a pedestrian is in the car's proximity.
According to GM engineers, the biggest challenge is "developing an active system that can distinguish a pedestrian from another vehicle"; otherwise, the sound will go off frequently, producing noise pollution instead.
The system, which was introduced in September 2010 on its test fleet of BlueOn electric hatchbacks, provides synthetic audio feedback mimicking the sound of an idling internal combustion engine.
In 2010 the car manufacturer decided to have a button on the Sonata Hybrid's instrument panel to turn the VESS on and off, but after the enactment of the Pedestrian Safety Enhancement Act of 2010, signed into law by President Obama in early 2011, and learning that the U.S. National Highway Traffic Safety Administration would not allow such switches to avoid the noise device to be turned off, Hyundai decided not to install the button, and the first Sonata Hybrids destined for the U.S. market had to be altered to remove the switch.
[58] Kia Niro HEV models sold in the US and UK in 2020/21 have been highly criticised by owners for the loud and antisocial reversing alert sounds, which can be heard from many 100s of feet away and yet are emitted from the front of the car.
The system developed makes a noise easy to hear for pedestrians to be aware of the vehicle approaching, but the warning sounds do not distract the car occupants inside.
[16] Nissan removed the ability to disable the pedestrian alert between model year 2011 and 2012 in anticipation of the U.S. ruling to be issued by the National Highway Traffic Safety Administration.
Nancy Gioia, Ford's Director for Global Electrification commented that "car companies should consider standardising tones from future hybrids and electrics to avoid a cacophony of confusion on the streets.
"[76] Several anti-noise and electric car advocates have opposed the introduction of artificial sounds as warning for pedestrians, as they argue that the proposed system will only increase noise pollution.
