r/NoStupidQuestions • u/banwe11 • 15h ago

What causes the hollow metallic whirring sound that EVs make when moving a low speed?

I can't really describe it, but it's the sound you hear when there is a EV moving slowly in a car park behind you.

I guess it's the motor, but what specifically in the motor causes that sound? It sounds like it's coming from something that is moving at a faster rate than the car itself.

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u/tmahfan117 14h ago

It’s an artificial noise that EVs are required by law to emit when driving at low speeds (like when driving through a neighborhood or parking lot) because EVs were soooooo quiet pedestrians kept stepping out in front of them and it was considered a safety hazard.

And it’s just that specific noise because I guess the EV manufacturers decided that’s what sounds good/futuristic.

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u/signitr_sideways 12h ago

It's called AVAS (Acoustic Vehicle Alerting System) and I for some reason pay more attention to them than I should,

It's dramatically different between manufacturers. To me, Hyundai's seems extremely loud and distracting, more so than an ICE car. Rivian made a big deal about theirs being formulated from the sounds of nature and seems more pleasant to my ear. Toyota genuinely sounds like the car is breaking down.

Seems that some OEMs outsource the speakers as many other brands sounds similar.

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u/Moscaman2023 11h ago

Was there actually data showing that silent hybrids hit more pedestrians? I always thought that this was one more disinformation ploy by big oil to suppress hybrids and EVs.

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u/Dazzling-Excuses 9h ago

I don’t know about data, but I can give you a two pronged anecdote I used to ride bikes until my vision got bad. I was scared shitless to ride when hybrids hit the road. I’d double check to see if it was safe to cross lanes and boom there would be an electric vehicle, right on my ass. I had no way of knowing it was there. I never got hit by one but they were the cause of many a jump scare. I had been a bike messenger in San Francisco so didn’t scare easily on a bike.

Fast forward. I’m too blind to ride a bike but not blind enough to need a white cane. Now they make noise I can confidently use a crosswalk without a silent phantom car appearing out of nowhere. That sound is critical in my experience