AVAS Explained: Understanding the Acoustical Vehicle Alerting System

As automotive technology continues to evolve, so too does our approach to vehicle safety. One of the more recent developments in this space is the Acoustical Vehicle Alerting System (AVAS)—also known as a Pedestrian Warning System (PWS). While still a relatively new concept for many drivers, AVAS is becoming a vital component of electric vehicle (EV) design worldwide.

In this article, we’ll explore what AVAS is, how it works, and why it’s now a legal requirement in many countries.

What Exactly is AVAS?

AVAS is a sound-based safety system fitted to electric and hybrid vehicles. Unlike traditional petrol or diesel cars, electric vehicles produce minimal noise when operating at low speeds. This presents a hazard to pedestrians, cyclists, and visually impaired individuals who rely on sound cues to detect nearby traffic.

AVAS solves this issue by emitting artificial sound to indicate the presence and movement of an EV, making roads safer for everyone.

How does AVAS Operate?

AVAS technology uses an external speaker system, strategically positioned on the vehicle, to broadcast artificial engine-like sounds. These audio cues are typically activated when the vehicle is travelling below 20 km/h (around 12 mph)—the speed range where electric cars are often virtually silent.

There are two main types of AVAS units:

• Integrated systems, where the controller and speaker are combined into a single unit
• Separate (passive) systems, where a dedicated controller communicates with the speaker via protocols such as CAN bus

Companies like Seger A.S offer both variations, termed active and passive. The system uses real-time vehicle data—such as throttle input, gear selection, and movement status—to determine when to trigger sound emissions. More advanced setups also support cybersecurity measures and over-the-air software updates, ensuring long-term compliance and functionality.

Why is AVAS a Legal Requirement?

The need for AVAS arises from the increasing adoption of quiet-running electric and hybrid vehicles. With minimal noise output, these vehicles can pose an unintentional threat to those who rely heavily on auditory awareness to navigate safely.

To mitigate this risk, regulatory bodies have made AVAS mandatory for all new EVs and hybrids. This proactive safety measure is especially important for the protection of vulnerable road users, including children, the elderly, and those with visual impairments.

AVAS Compliance: Regulations and Global Standards

AVAS is not just a recommended feature—it is now enshrined in law across various regions. Key regulations include:

• United Nations Economic Commission for Europe (UNECE) regulation R138 (Europe and other participating countries)
• FMVSS No. 141 (United States)

These standards dictate when AVAS must be active, what frequencies are permitted, and how loud the alerts must be to ensure audibility without contributing to noise pollution.

Other nations—including Japan and members of the European Union—have adopted similar frameworks, aligning their AVAS requirements to create global consistency.

In Conclusion

Acoustic Vehicle Alerting Systems represent more than just another tech upgrade—they symbolise a shift in how we think about safety in the age of electric mobility. As governments around the world enforce stricter vehicle noise regulations, AVAS has become a critical component of EV design.

By combining sound engineering with legislative oversight, AVAS helps create a safer and more inclusive environment for all road users. Its adoption is not only smart—it's essential.