A little more to this than I knew.
en.wikipedia.org
Background
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.
[8] 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.
[9]
This problem is not exclusive to electric vehicles. In 2007 research at the
Technical University 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.
[10][11]
Tesla
Tesla, Inc. introduced a Pedestrian Warning System feature in September 2019
[73] that emits warning sounds when the vehicle is traveling below 19mph/32km/h.
[74] In 2021 Tesla announced plans to retrofit the system onto select older Model 3 and Model Y vehicles from 2019.
[75] The feature is currently available on all Tesla models:
Tesla Model S,
[74] Tesla Model 3,
[76] Tesla Model X,
[77] and
Tesla Model Y.
[78]
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 U.S. pending legislation that would require generated warning sounds with no off switch for the driver.
[82]
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
."
[13]