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.
- 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
- 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.
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.
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:
- 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.
- 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.
- 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.
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
- The Driving Sound of the first electrified BMW M (Hans Zimmer) - BMW M
- The Sound of the BMW Concept i4 - Hans Zimmer & Renzo Vitale - BMW Group
- Iconic Sounds by Hans Zimmer in the BMW iX M60 (all modes) - Kroysplace
- Porsche Taycan - Porsche Electric Sport Sound - Autowizja
- Porsche Taycan Turbo S - the future sound - Automann-TV
- Nissan “Canto” AVAS explained (Paul Speed-Andrews) - Nissan Greece
- Mercedes-Benz e-sound - AVAS for electric cars - The Wheel Network
- Audi e-tron artificial engine sound - Car Tech Connect
- Jaguar I-PACE - Safety Sounds for the Visually Impaired - Jaguar (official)
- Hyundai Ioniq 5 - pedestrian/reverse sound - Ever
- Hyundai Ioniq 5 N - Active Sound demo - DPCcars
- Kia e-Niro - virtual engine / VESS warning sound - crospotter13
- MINI Cooper SE - reverse AVAS - Ever
- Fiat 500e - pedestrian alert + Italian chime - TFLEV
- BYD Seal - AVAS low-speed sound (OTA update) - Ludicrous Feed
- BYD Seal - AVAS toggle walkthrough - Ludicrous Feed
- Lucid Gravity - EV pedestrian sound - car du jour
- Toyota bZ - pedestrian warning sound - Ever
- Toyota hybrid/EV warning sounds demo - Toyota KC Region
- Ford F-150 / Mach-E pedestrian + reverse speaker - Jake Reviews All
- Volvo - a calming choir. - Carless Stockholm
Trucks & buses
- Volvo FH Electric - review covering its AVAS - Rubetrans Logistics
- Metroline BYD electric double-decker, London - SHOWBUS.com
- Tesla Semi close-up - “notice how little sound there is?” - My Tesla Adventure
Explainers, accessibility & context
- Why do some cars have speakers outside? (Tesla Boombox & AVAS) - DriveOS
- HARMAN HALOsonic - how external EV sound is engineered - HARMAN
- AVAS vs. Rear Cross-Traffic Alert explained - Gateway Toyota
- Electric cars and the blind - Fully Charged / Everything Electric
- Cities Aren’t Loud: Cars Are Loud (EV section) - Not Just Bikes
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.
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.
