why do electric cars make no noise after an update?

Q: why do electric cars make no noise after an update?

Electric cars are inherently quiet because their electric motors don't produce the combustion noise of gasoline engines. Recent updates mandate artificial sounds, known as Acoustic Vehicle Alerting Systems (AVAS), to alert pedestrians and cyclists to their presence at low speeds, as they are otherwise too silent to be easily detected.

The Deep Dive

Electric vehicles (EVs) operate using electric motors, which are fundamentally different from the internal combustion engines (ICE) found in traditional cars. ICEs create noise through the controlled explosions of fuel and air within cylinders, a process that generates significant mechanical and exhaust sounds. Electric motors, conversely, work by using electromagnetic forces to rotate a shaft. This process is remarkably smooth and quiet, producing only a faint hum or whine, especially at lower speeds. The absence of exhaust systems, mufflers, and engine revving means EVs are inherently much quieter. However, this silence became a safety concern. At speeds below approximately 19 miles per hour (30 km/h), an EV can be almost undetectable to pedestrians, particularly those with visual impairments. To address this, regulatory bodies worldwide have mandated the use of Acoustic Vehicle Alerting Systems (AVAS). These systems broadcast artificial sounds, often a synthesized hum or tone that changes with the car's speed and acceleration, ensuring that the vehicle's presence is audible in its surroundings.

Why It Matters

The quiet nature of electric cars presents a unique safety challenge. Pedestrian and cyclist safety is paramount, and the lack of audible cues from silent EVs necessitates technological solutions like AVAS. These systems ensure that vulnerable road users can detect approaching vehicles, preventing accidents. Furthermore, the integration of these sounds allows manufacturers to add a distinctive auditory signature to their EV models, contributing to brand identity. Understanding the science behind EV quietness and the rationale for mandated sounds highlights the ongoing innovation in automotive safety.

Common Misconceptions

A common misconception is that electric cars were always designed to be silent and that the added sounds are a recent, unnecessary complication. In reality, the extreme quietness of early EVs was an unintended consequence of their efficient electric powertrains, which initially raised safety alarms. Another myth is that all EVs are completely silent. While they are significantly quieter than gasoline cars, their electric motors do produce some subtle sounds, and the mandated AVAS systems actively generate audible alerts at low speeds, making them far from silent.

Fun Facts

The sounds generated by AVAS are carefully designed to be audible but not overly intrusive or annoying to the general public.
Regulations often specify that the AVAS sound must be recognizable as a vehicle approaching and must vary with the car's speed.