Electric vehicle warning sounds

As a result of increased sales of full electric vehicle and hybrid electric vehicles in several countries, some members of the blind community have raised concerns about the noise reduction when those vehicles operate in all-electric mode, as blind people or the visually impaired consider the noise of combustion engines a helpful aid while crossing streets and think quiet hybrids could pose an unexpected hazard. Although a 2009 study found no statistically significant difference in pedestrian crashes involving quiet hybrid vehicles when compared to noisier vehicles when both types of vehicles were travelling in a straight line, it found a doubling of hybrid vehicle pedestrian crashes when reversing or parking etc. at slow speeds. This problem is not exclusive to electric vehicles. In 2007, research at the Technical University of Munich showed that ordinary vehicles in background noise are often detected too late for safe accident avoidance. The researchers measured the distance at which vehicles approaching pedestrians became audible with minimal background noise. These distances were then compared to the stopping distances of the respective cars and an algorithm was proposed to estimate them based on auditory masking. 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. This research project was funded by the National Federation of the Blind. The experiment consisted of making audio recordings of a Toyota Prius and combustion engine Honda Accord approaching from two directions at to ensure that the hybrid car operated only with its electric motor. Then, test subjects in a laboratory listened to the recordings and indicated when they could hear from which direction the cars approached. Subjects could locate the hum of the internal combustion engine car at away, but could not identify the hybrid running in electric mode until it came within , leaving just less than two seconds to react before the vehicle reached their position. 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. Under this condition, the hybrid needed to be 74 percent closer than the conventional car before the subjects could hear from which direction the cars approached. Subjects could correctly judge the approach of the combustion car when it was about away. This result means that under closer to normal environmental noise, a pedestrian would not be able to correctly determine the hybrid's approach until it was one second away. 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. After the test, several of them changed their opinion and said that this issue was less of a problem than they expected. Nevertheless, some test drivers said they experienced incidents of not being noticed, while others said they had taken extra care in their driving with regard to this issue. ==Regulations==

Since 2009 the Japanese government, the US Congress and the European Commission are exploring legislation to establish a minimum level of sound for plug-in electric and hybrid electric vehicles when operating in electric mode, so that blind people and other pedestrians and cyclists can hear them coming and detect from which direction they are approaching. Tests have shown that vehicles operating in electric mode can be particularly hard to hear below . European Union In 2011, the European Commission drafted a guideline for acoustic vehicle alerting systems (AVAS). 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 ongoing research activities and the development of globally harmonised device performance specifications. The guidelines are intended for hybrid electric and pure electric highway-capable vehicles. The guideline recommends that the AVAS should automatically generate a continuous sound in the minimum range of vehicle speed from start-up to approximately and during reversing, if applicable for that vehicle category, and lists the types of sounds that are not acceptable. It also states that the AVAS may have a pause switch to stop its operation temporarily. 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 AVAS systems to be compulsory in the future. Now an agreement has to be negotiated with European Union countries. The approved amendment establishes that "the sound to be generated by the AVAS should be a continuous sound that provides information to the pedestrians and vulnerable road users of a vehicle in operation. The sound should be easily indicative of vehicle behaviour and should sound similar to the sound of a vehicle of the same category equipped with an internal combustion engine." Japan Beginning in July 2009, the Japanese government began assessing possible countermeasures through the Committee for the Consideration of Countermeasures Regarding Quiet Hybrid and Other Vehicles, and in January 2010, the Ministry of Land, Infrastructure, Transport and Tourism issued guidelines for hybrid and other near-silent vehicles. United Kingdom The Department for Transport (DfT) commissioned research to gather statistics on accidents involving electric vehicles with pedestrians who are blind or vision impaired to determine whether the perceived accident risk is real and whether electric and hybrid cars are more difficult to detect audibly than conventional internal combustion engine vehicles. The DfT goal was to use the findings to establish what sort of sound should be fitted to electric vehicles. 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. United States The Pedestrian Safety Enhancement Act of 2010 was approved by the US Senate by unanimous consent on December 9, 2010, and passed by the House of Representatives by 379 to 30 on December 16, 2010. The act does not stipulate a specific speed for the simulated noise but requires the US Department of Transportation to study and establish a motor vehicle safety standard that would set requirements for an alert sound that allows blind and other pedestrians to reasonably detect a nearby electric or hybrid vehicle, and the ruling must be finalised within eighteen months. The bill was signed into law by President Barack Obama on January 4, 2011. A proposed rule was published for comment by the National Highway Traffic Safety Administration (NHTSA) in January 2013. It would require hybrids and electric vehicles travelling at less than to emit warning sounds that pedestrians must be able to hear over background noises. The agency selected 30 km/h as the limit because, according to NHTSA measurements, this is the speed at which the sound levels of the hybrid and electric vehicles are approximately equivalent to the sound levels produced by similar internal combustion vehicles. In February 2013, the Association of Global Automakers and the Alliance of Automobile Manufacturers, which submitted a joint comment to the NHTSA, announced their support to the rule, but asked the NHTSA to find a noise level that effectively alerts pedestrians without being excessively loud to others inside and outside of the vehicle. They also commented that the rule is too complicated, unnecessarily prescriptive, and it will cost more than necessary. 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." In addition, the vehicle manufacturers requested the NHTSA to make the new sound system required by 2018 instead of 2014. In November 2015, the NHTSA rescheduled one more time because additional coordination was necessary. A final ruling was delayed at least until mid-March 2016. After several additional delays, the National Highway Traffic Safety Administration issued its final ruling in February 2018. It requires hybrids and electric vehicles travelling at less than to emit warning sounds that pedestrians must be able to hear over background noises. The regulation requires full compliance in September 2020, but 50% of "quiet" vehicles must have the warning sounds by September 2019. ==Specific systems==

Enhanced Vehicle Acoustics 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). The device makes hybrid electric vehicles sound more like conventional internal combustion engine cars when the vehicle goes into the silent electric mode (EV mode), but at a fraction of the sound level of most vehicles. At speeds higher than between the sound system shuts off. The system also shuts off when the hybrid combustion engine is active. 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. If the car is moving forward, the sounds are only projected in the forward direction; and if the car is turning left or right, the sound changes on the left or right appropriately. 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." One of the EVA's external sound systems was designed specifically for the Toyota Prius. The ECTunes system, and most others so far disclosed, use a control box with software, digital amplifiers, and weather-friendly external speakers. ECTunes' system connects to the car and reads speed and acceleration, shutting down when the car reaches Cross-over speed as set by existing regulation as well as regulation under development such as Quiet Road Transport Vehicles (QRTV), at which point the tires and wind are making noise of their own. The company is currently selling products to OEMs, mainly small series production, and to the after market, and also has a new mass production unit in prototype stage The company ceased operations in 2016. Fisker Automotive has an automatic warning sound-generator. includes a manually activated warning sound. Fisker Automotive developed a sound-generator that was incorporated in its Fisker Karma luxury plug-in hybrid electric vehicle, released in 2011. According to the car manufacturer, the sound is designed to both alert pedestrians and enhance the driver experience, and the warning noise will be emitted automatically. The Fisker Karma emits a sound through a pair of external speakers embedded in the bumper. According to a company spokesman the sound is a mix between a "Formula One car and a starship". The developing process took between nine months and a year, and three sound companies sent in synthesised WAV file samples that were evaluated by Fisker employees and executives. The prospective sounds were studied in an audio chamber to allow engineers to evaluate the sounds without other noise interfering. After testing the candidate sounds in different locations relative to the vehicle, Fisker fine-tuned the final sound with its own equipment. The warning sound is activated when the car is travelling at less than . Ford The 2012 Ford Focus Electric was planned to include warning sounds for pedestrians. Ford Motor Company developed four alternative sounds, and in June 2011 involved the electric car fans by asking them to pick their favorite from the four potential warning sounds through the Focus Electric Facebook page. 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. General Motors General Motors' first commercially available plug-in hybrid electric vehicle, the Chevrolet Volt, introduced in December 2010, includes warning sounds for pedestrians. GM's system is called Pedestrian-Friendly Alert System and it is manually activated by the driver, but future generations will probably include a passive system. 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. The system uses the car's horn to emit a series of warning chirps, like a low tone of a horn, enough to provide an alert but not to startle. 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. Hyundai Hyundai developed a warning noise called the Virtual Engine Sound System (VESS). 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. The 2011 Hyundai Sonata Hybrid is the first mass production car manufactured by Hyundai to include the warning sound system. 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 US 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 US market had to be altered to remove the switch. Kia 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. Lotus Engineering Lotus Engineering, a consultancy group of British sports car manufacturer Lotus Cars, partnered in 2009 with Harman Becker, a producer of audio systems, to develop and commercialise a synthetic automotive audio systems. Lotus has worked on a number of hybrid and electric vehicles and its engineers thought they would be safer if these vehicles made a noise while moving around the factory. Lotus' synthetic sound system was incorporated in the Lotus Evora 414E Hybrid, a concept plug-in hybrid unveiled at the 2010 Geneva Motor Show. The system, called HALOsonic Internal and External Electronic Sound Synthesis, is a suite of noise solutions that uses patented technologies from Lotus and Harman International. The audio system generates engine sounds inside the vehicle through the audio system. The system also generates the external sound through speakers mounted at the front and rear to provide a warning to increase pedestrian safety. The system comes with four driver-selectable engine sounds, two of which have been designed to have characteristics of a multi-cylinder conventional V6 and V12 engine. Nissan equipped with warning sound pause switch. Vehicle Sound for Pedestrians (VSP) is a Nissan-developed warning sound system in electric vehicles. The Nissan Leaf was the first car manufactured by Nissan to include VSP, and the electric car includes one sound for forward motion and another for reverse. The VSP was also used in the Nissan Fuga hybrid launched in 2011. 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. Nissan explained that during the development of the sound they studied behavioural research of the visually impaired and worked with cognitive and acoustic psychologists, including the National Federation of the Blind (NFB), the Detroit Institute of Ophthalmology, experts from the Vanderbilt University Medical Center and a Hollywood sound design studio. Nissan's Vehicle Sound for Pedestrians is a sine-wave sound system that sweeps from 2.5 kHz at the high end to a low of 600 Hz, a range that is easily audible across age groups. Depending on the speed and whether the Leaf is accelerating or decelerating, the sound system will make sweeping, high-low sounds. For example, when the Leaf is started the sound will be louder, and when the car is in reverse, the system will generate an intermittent sound. The sound system ceases operation when the Nissan Leaf reaches and engages again as the car slows to under . For the 2011 Leaf, the driver could turn off sounds temporarily through a switch inside the vehicle, but the system automatically reset to "On" at the next ignition cycle. The system is controlled through a computer and synthesizer in the dash panel, and the sound is delivered through a speaker in the front driver's side wheel well. Nissan said that there were six or seven finalist sounds, and that sound testing included driving cars emitting various sounds past testers standing on street corners, who indicated when they first heard the approaching car. After Nissan's new sounds were publicised, the US National Federation of the Blind issued a statement saying that "while it was pleased that the alert existed, it was unhappy that the driver was able to turn it off." For the 2014 UK model of the car, the VSP system is enabled by default, though a button on the dash permits drivers to disable the system until the next time the car is switched on. Tesla Tesla, Inc. introduced a Pedestrian Warning System feature in September 2019 that emits warning sounds when the vehicle is traveling below 19mph/32km/h. In 2021, Tesla announced plans to retrofit the system onto select older Model 3 and Model Y vehicles from 2019. The feature is currently available on all Tesla models: Tesla Model S, Tesla Model X, and Tesla Model Y. Toyota is available for Japanese consumers. Toyota Motor Company teamed up with Fujitsu Ten to develop an automatic warning system for hybrids and electric vehicles to alert pedestrians when the car is propelled by its electric motor. The companies also studied the development of a system that would change the alarm's tune and volume with the assistance of an obstacle-detection radar. In August 2010 Toyota began sales of an onboard device designed to automatically emit a synthesised sound of an electric motor when the Prius is operating as an electric vehicle at speeds up to approximately . The device will be available in Japan through authorised Toyota dealers and Toyota genuine parts & accessories distributors for retrofitting on the third-generation Prius at a price of (~) including the consumption tax. The alert sound rises and falls in pitch according to the vehicle's speed, thus helping indicate the vehicle's proximity and movement to nearby pedestrians. Toyota is planning to use other versions of the device for use in hybrid electric vehicles, plug-in hybrids, electric vehicles as well as fuel-cell hybrid vehicles planned for mass production. The device meets the 2010 government regulations issued for hybrid and other near-silent vehicles. Toyota's Vehicle Proximity Notification System (VPNS) was introduced in the United States in all 2012 model year Prius family vehicles, including the Prius v, Prius Plug-in Hybrid and the standard Prius. The system is being introduced to comply with the Pedestrian Safety Enhancement Act of 2010. Volkswagen Volkswagen offers a so-called e-Sound module on its electric and hybrid vehicles such as the e-Up, e-Golf and the GTE hybrid range. It provides a pedestrian warning sound up to 30 km/h. Other manufacturers Think Global, a manufacturer of electric cars already in the market, is assessing this safety issue. Ford Motor Company is developing a system for emitting external sounds to future hybrids and electrics, including its Focus BEV, scheduled for 2011, and a next-generation hybrid and plug-in hybrid vehicle planned for 2012. 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." ==Criticism and controversy==

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. They also opposed US pending legislation that would require generated warning sounds with no off switch for the driver. Robert S. Wall Emerson of Western Michigan University has argued that several high-end gasoline-powered luxury cars are already quieter than hybrids, and according to his most recent studies, hybrid SUVs were noisier than many internal-combustion vehicles. He concludes that pedestrian safety is not a hybrid issue but rather "a quiet car issue". ==Market availability==

, most of the hybrids and plug-in electric and hybrids sold in the US market make warning noises using a speaker system. Tesla Motors, Volkswagen and BMW do not currently include warning sounds in their electric-drive vehicles, as all of them decided to add artificial sounds only when required by regulation. == See also ==