# The Sound of Silence: How the World's Electric Cars Learned to Speak
AVAS = Acoustic Vehicle Alerting System: an artificial sound an electric or hybrid vehicle emits at low speed (and in reverse) so people nearby can hear it coming.
You step toward a crossing, glance up the road, and a car is already there, gliding past in near-total silence. No engine sound, just the hiss of tyres. For most of us it's a small surprise. For a blind pedestrian or a child near the kerb, there's no warning at all.
The car industry's answer is a piece of safety engineering called **AVAS** (Acoustic Vehicle Alerting System). It's why your neighbour's new EV hums or whirs as it pulls out of the drive: why those sounds exist, where they're required, and how carmakers turned a legal obligation into a branding playground, complete with a Hollywood composer, a Paris music lab, and one sound so futuristic that test subjects looked up at the sky.
## What Exactly Is AVAS?
An Acoustic Vehicle Alerting System is a speaker-and-software package that makes an electric or hybrid vehicle emit a deliberate sound at low speed and when reversing. Below roughly 20–30 km/h (about 12–19 mph), an EV's tyres and wind noise are too faint to warn anyone nearby, so the AVAS fills that gap with an engineered tone that **rises in pitch and volume as the car accelerates** and changes character in reverse.
What makes a good AVAS sound:
- **Detectable** it must cut through city background noise without being annoying.
- **Directional and informative** listeners should be able to tell where the car is and whether it's speeding up or slowing down.
- **On-brand** increasingly, manufacturers want the sound to *feel* like their marque.
AVAS is not the same as the *interior* "engine" sounds many EVs now offer (think Hyundai's Active Sound Design or BMW's cabin soundscapes). AVAS faces *outward*, to protect people outside the car, and in almost every market the driver is **not allowed to switch it off**.
## Why It Matters: The Safety Case
The push for AVAS wasn't a marketing idea. It came from hard safety data and years of advocacy by blind and low-vision communities.
- **A landmark 2008 study at UC Riverside,** funded by the U.S. National Federation of the Blind, found that a Prius in electric mode could only be heard when it was **11 feet away**, versus **36 feet** for a petrol Honda Accord, leaving pedestrians a fraction of the reaction time.
- **The U.S. NHTSA** repeatedly found hybrids more likely than petrol cars to hit pedestrians during low-speed maneuvers (turning, slowing, reversing). Its research (DOT HS 812 371) put the odds roughly **20% higher overall and about 50% higher** for those low-speed situations, with elevated risk for cyclists too.
- **In its rulemaking for the U.S. standard, NHTSA** estimated that without a sound requirement, quiet vehicles would cause on the order of **2,800 additional pedestrian and cyclist injuries** a year once they became common, and that AVAS was a cost-effective way to prevent them.
Advocacy did the rest. In the U.S., the National Federation of the Blind helped drive the **Pedestrian Safety Enhancement Act of 2010**. In the U.K., **Guide Dogs** campaigned hard and later helped *design* the sound for London's first electric bus route. Canada's **CNIB** played the same role north of the border. AVAS is accessibility legislation that everyone benefits from.
## The Global Rulebook: 20 km/h vs. 30 km/h
Almost every major market now mandates AVAS, though they split into two technical camps that disagree mainly on the **cut-off speed**.
UN Regulation No. 138
EU · UK · JAPAN · S. KOREA · AUSTRALIA · MOST OF THE WORLD
0–20 km/h
- Sound required from start-up to 20 km/h, and when reversing
- Must rise in pitch/volume with speed; min ≈56 dB(A) at 20 km/h, max 75 dB(A)
- EU: mandatory on new vehicle types Jul 2019; all new cars Jul 2021
- Driver "pause" switch heavily restricted
FMVSS No. 141
UNITED STATES · CANADA (CMVSS 141)
0–30 km/h + stationary
- Sound required up to 30 km/h (18.6 mph), a higher threshold than UN R138
- Also required while the vehicle is stationary with the system active
- U.S. compliance phased in, reaching full coverage by September 2020
- No driver off-switch permitted
**Around the world:** Japan issued early guidelines as far back as 2010 and aligns with UN R138. China published a national AVAS standard (GB/T 37153-2018, a *recommended* standard) effective July 2019, also using a 20 km/h threshold. The UK carried UN R138 into its post-Brexit GB type-approval scheme.
And Australia's ADR 113/00 took effect for new models in November 2025, notably spelling out that trucks and buses are covered too, with the government estimating it will prevent dozens of deaths and thousands of injuries over coming decades.
### How we got here: A timeline of AVAS mandates
A global mandate, market by market
- 2010: Japan issues the first national guidelines for warning sounds on quiet vehicles.
- 2016–17: U.S. finalises FMVSS 141; the UN adopts Regulation No. 138 for the rest of the world.
- Jul 2019: EU requires AVAS on all newly type‑approved electric & hybrid models.
China published a national, recommended AVAS standard GB/T 37153-2018.
- Sep 2020: U.S. reaches full AVAS compliance for all quiet vehicles.
- Jul 2021: EU extends the rule to every new electric/hybrid car registered, not just new types.
- 2022: Canada (CMVSS 141) and the UK's post‑Brexit GB scheme lock in their requirements.
- Nov 2025: Australia's ADR 113/00 takes effect for new models, explicitly including trucks & buses.
*(A few national fine points — exact binding dates in Japan and South Korea, and whether China pairs its recommended standard with a mandatory one — vary or are less clearly documented; the thresholds and direction of travel, however, are consistent worldwide.)*
## How Carmakers Found Their Voice
The regulation dictates *how loud* and *up to what speed* but leaves the **character** of the sound wide open. That blank canvas sparked an unexpected creative competition.
- **BMW — IconicSounds Electric.**
BMW hired Oscar-winning film composer **Hans Zimmer**, working with in-house sound designer Renzo Vitale, to score its EVs (i4, iX, i5). Drivers can even select different cinematic soundscapes per drive mode.
- **Nissan — "Canto."**
Italian for *"I sing,"* Canto is a two-tone signature first developed with New York's Made Music Studio and refined for Europe by Nissan's own engineers. Nissan later repurposed the idea into *ANIMALERT*, a sound aimed at warning **wildlife**.
- **Jaguar — and the sound that looked at the sky.**
Jaguar spent four years on the I-PACE's Audible Vehicle Alert System, co-testing with Guide Dogs UK. Its first, spacey prototype was scrapped after testers instinctively **looked upward** for a hovering craft instead of toward the road.
- **Renault — Z.E. Voice.**
Renault was an early mover, fitting a pedestrian sound to the Zoe back in **2012**, years ahead of any mandate, in a long-running collaboration with the Paris acoustics-and-music institute **IRCAM**.
- **Volkswagen — the ID. family.**
VW developed its futuristic hum with composer-producer **Leslie Mandoki**, unveiling it in 2019.
- **Porsche — purist to the core.**
For the Taycan, Porsche's Weissach team built the sound **only from real vehicle components** (motor, transmission, tyres), refusing both synthesizers and celebrity composers. (Its optional *Electric Sport Sound* is a separate, driver-facing enhancement, distinct from the mandatory AVAS.)
- **Volvo — a calming choir.**
Volvo's Active Sound Experience studio in Gothenburg built the EX30 and EX40 (XC40 Recharge) sound from a human vocal sample, layered into a slowly pulsing choral tone designed to soothe rather than startle, audible from about six feet and fading out near 29 km/h. A Volvo patent spells out the philosophy: shape the car's own road, tyre and motor noise into something pleasant, explicitly not a "spaceship" sound or a "branded" jingle. (It's the same team whose turn-signal click began life as a spruce twig snapping in a Swedish forest; they recorded 300 sticks to find the right one.)
- **Audi, Mercedes-Benz and the engineers' approach.**
Audi's *e-sound* layers dozens of recordings, projected from a speaker ahead of the front wheel. Mercedes tunes each EQ model's *e-sound* in an anechoic chamber using a binaural "dummy head," and pointedly **rejected** faking a combustion engine.
- **Hyundai & Kia — mind the distinction.**
Their exterior pedestrian warning (sometimes badged VESS) is separate from the *interior* Active Sound Design profiles (Stylish/Dynamic/Cyber on the EV6; simulated gearshifts on the Ioniq 5 N).
- **Tesla — the Boombox saga.**
Tesla added an external speaker around 2019, then let owners pipe custom audio through it via "Boombox": goat bleats, applause, you name it. The fun ran into the law: in 2022 NHTSA recalled roughly **578,000** cars because Boombox could play *while driving* and mask the mandatory warning tone. Tesla limited it to Park via an over-the-air update.
Others are distinctive in their own right: the Fiat 500e adds an Italian-flavoured musical motif, Lucid leans futuristic, Polestar insists on "responsible" non-intrusive design (explicitly no spaceship sounds), and Toyota equips its hybrids and the bZ range with a gentle low-speed hum.
## Beyond Cars: Trucks, Vans & Buses
Cars get most of the attention, but the same rules apply to heavy vehicles, and arguably matter *more* there. A silent 40-tonne truck is a far bigger surprise to a pedestrian than a silent hatchback, and researchers (at TU Dresden and Chalmers, the latter with Scania) have shown that simply copying a car's high-pitched AVAS onto a truck is a mistake: pedestrians expect **low-frequency sound that conveys mass**, and an under-pitched truck can be mistaken for something small and slow.
- **Volvo Trucks**
built a bespoke **four-sound suite** (moving, idling, reversing, transitions) for its FH/FM/FE/FL Electric range, deliberately engineering the sounds **not to penetrate building walls** so electric trucks can make quiet night-time deliveries without waking residents.
- **Mercedes-Benz Trucks**
gave the eActros front and rear speakers that **exceed** the UN minimum by 10–15 dB. The flip side: in early 2026 Mercedes had to recall its **eSprinter** van because the **reverse** alert was too *quiet* to comply: proof that AVAS is an enforced standard, not a token gesture.
- **Tesla Semi**
as a U.S. Class-8 electric truck, falls under the same FMVSS 141 low-speed requirement, even if Tesla hasn't publicised a signature sound for it.
- **Buses** got the most community-driven treatment: **Transport for London** trialled a custom electric-bus sound on **Route 100** in 2019, co-designed with **Guide Dogs UK** and accessibility groups, sounding below ~12 mph and at stops.
## The Ongoing Debate
AVAS carries some inherent tensions:
1. **Safety vs. noise pollution.** Cities fought hard to *reduce* traffic noise; deliberately adding sound back feels paradoxical. The regulations try to thread the needle with volume caps and sounds that fade out once tyre noise takes over above the threshold.
2. **The mute question.** Early EVs sometimes let drivers silence the system; modern rules largely forbid that, precisely because the people who benefit (pedestrians, the blind) aren't the ones holding the switch.
3. **Consistency vs. personality.** Accessibility advocates value **predictable** sounds people can learn to recognise, while brands want **distinctive** ones. The Tesla Boombox recall is the cautionary tale of personality going too far.
The likely future is more *standardised intent* with *branded execution*: recognisable as "a car approaching" to anyone, while still sounding unmistakably like a BMW, a Nissan, or a Porsche.
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## Hear It for Yourself: 29 AVAS Videos
The best way to understand AVAS is to listen. Below a ready-made YouTube playlist spanning passenger cars, trucks, buses, and explainers:
**Signature passenger-car sounds**
1. [The Driving Sound of the first electrified BMW M (Hans Zimmer)](https://www.youtube.com/watch?v=yNpeuQFfSlE) - *BMW M*
2. [The Sound of the BMW Concept i4 - Hans Zimmer & Renzo Vitale](https://www.youtube.com/watch?v=Ep-tlvql_j0) - *BMW Group*
3. [Iconic Sounds by Hans Zimmer in the BMW iX M60 (all modes)](https://www.youtube.com/watch?v=jqmN-2j2cb8) - *Kroysplace*
4. [Porsche Taycan - Porsche Electric Sport Sound](https://www.youtube.com/watch?v=LeUjeaCrxT8) - *Autowizja*
5. [Porsche Taycan Turbo S - the future sound](https://www.youtube.com/watch?v=fxSBMTwE858) - *Automann-TV*
6. [Nissan "Canto" AVAS explained (Paul Speed-Andrews)](https://www.youtube.com/watch?v=c0qGRUmhtY4) - *Nissan Greece*
7. [Mercedes-Benz e-sound - AVAS for electric cars](https://www.youtube.com/watch?v=k82rjRxl6Gk) - *The Wheel Network*
8. [Audi e-tron artificial engine sound](https://www.youtube.com/watch?v=MUcbXplAvSc) - *Car Tech Connect*
9. [Jaguar I-PACE - Safety Sounds for the Visually Impaired](https://www.youtube.com/watch?v=13JwfssNI3I) - *Jaguar (official)*
10. [Hyundai Ioniq 5 - pedestrian/reverse sound](https://www.youtube.com/watch?v=JtY6sVyA6yo) - *Ever*
11. [Hyundai Ioniq 5 N - Active Sound demo](https://www.youtube.com/watch?v=DSIguemKIbQ) - *DPCcars*
12. [Kia e-Niro - virtual engine / VESS warning sound](https://www.youtube.com/watch?v=NdZwVJPN0Ow) - *crospotter13*
13. [MINI Cooper SE - reverse AVAS](https://www.youtube.com/watch?v=Ov62ILHTc-o) - *Ever*
14. [Fiat 500e - pedestrian alert + Italian chime](https://www.youtube.com/watch?v=zo-RSW4kzVs) - *TFLEV*
15. [BYD Seal - AVAS low-speed sound (OTA update)](https://www.youtube.com/watch?v=CQwmDVC7auM) - *Ludicrous Feed*
16. [BYD Seal - AVAS toggle walkthrough](https://www.youtube.com/watch?v=mXxxVmETNdw) - *Ludicrous Feed*
17. [Lucid Gravity - EV pedestrian sound](https://www.youtube.com/watch?v=zlHdTUwFN9w) - *car du jour*
18. [Toyota bZ - pedestrian warning sound](https://www.youtube.com/watch?v=cicAEHML4Hk) - *Ever*
19. [Toyota hybrid/EV warning sounds demo](https://www.youtube.com/watch?v=80VKMkrJ6CA) - *Toyota KC Region*
20. [Ford F-150 / Mach-E pedestrian + reverse speaker](https://www.youtube.com/shorts/H_jZJxMrNrY) - *Jake Reviews All*
21. [Volvo - a calming choir.](https://youtu.be/1qRYuiAtP7g?si=kfBfVb6v7gUMjxi2&t=39) - *Carless Stockholm*
**Trucks & buses**
22. [Volvo FH Electric - review covering its AVAS](https://www.youtube.com/watch?v=6OxZiFSSKHQ) - *Rubetrans Logistics*
23. [Metroline BYD electric double-decker, London](https://www.youtube.com/watch?v=LsoRYWcD0O8) - *SHOWBUS.com*
24. [Tesla Semi close-up - "notice how little sound there is?"](https://www.youtube.com/watch?v=dP0vIH8r-tE) - *My Tesla Adventure*
**Explainers, accessibility & context**
25. [Why do some cars have speakers outside? (Tesla Boombox & AVAS)](https://www.youtube.com/watch?v=LU-8RUwAl9g) - *DriveOS*
26. [HARMAN HALOsonic - how external EV sound is engineered](https://www.youtube.com/watch?v=_gBi_rNGoQQ) - *HARMAN*
27. [AVAS vs. Rear Cross-Traffic Alert explained](https://www.youtube.com/watch?v=VHcnaaehxow) - *Gateway Toyota*
28. [Electric cars and the blind](https://www.youtube.com/watch?v=95O14kUgmBI) - *Fully Charged / Everything Electric*
29. [Cities Aren't Loud: Cars Are Loud (EV section)](https://www.youtube.com/watch?v=CTV-wwszGw8) - *Not Just Bikes*
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## The Takeaway
AVAS gives back a layer of safety that the electric revolution quietly removed, without dragging combustion noise back into our streets. And the sounds themselves turned out to be more than compliance: even a legally mandated alert can carry a brand's character, whether scored by Hans Zimmer or built from the whir of a real motor.
So the next time an EV slips past you with a soft, rising hum, listen closely. That sound was argued over by safety regulators, blind-rights campaigners, acoustic engineers and film composers, all so that you, and everyone around you, can simply hear it coming.
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*Sources: UNECE Regulation No. 138; EU Regulation 540/2014; U.S. NHTSA FMVSS No. 141 and rulemaking dockets; UC Riverside / National Federation of the Blind (2008); manufacturer press materials (BMW, Nissan, Jaguar, Renault, Volkswagen, Porsche, Audi, Mercedes-Benz, Volvo Trucks, Daimler Truck); Transport for London. Some national implementation dates vary by market; figures are rounded for readability.*