What is acoustic vehicle alerting systems and Why Do We Use Them?

An Acoustic Vehicle Alerting System (AVAS) is an advanced sound technology equipped in electric and hybrid vehicles to offset their low noise levels at reduced speeds. It produces synthesized sounds, akin to those of traditional combustion engines or other recognizable noises, to enhance pedestrian safety by making the vehicle’s presence known.

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AVAS employs external loudspeakers to emit sounds whose intensity and pitch vary according to the vehicle’s speed, direction, and proximity to obstacles, ensuring that pedestrians, cyclists, and other road users can hear the vehicle approaching. Primarily operational at lower speeds, where the absence of tire and wind noise may not alert nearby individuals, the system dynamically adjusts or turns off at higher speeds when the vehicle naturally becomes audible due to environmental noise contributions.

Legislation all over the world has made AVAS mandatory for vehicles with an electric mode of operation, imposing a minimum noise level. Several standards and regulations have been formulated over the past years to define electric vehicle warning sounds and methods of testing.

Early AVAS systems allowed the driver to interact with the AVAS system, for example the Renault Zoe had 3 sounds that could be chosen, this and the Nissan Leaf allowed drivers to switch off the sound. Over the last few years as AVAS legislation has been passed worldwide, this user interaction has been removed.

Electric vehicles including battery electric vehicles (BEV) and plug-in hybrids (PHEV) all require AVAS today. Therefore, growth in these markets is the main driver for growth of AVAS systems. BEVs are expected to dominate the market through the forecast period.

Almost 500 million fully integrated AVAS modules are expected to ship from to in total. Therefore it is a significant market opportunity.

What Technology is Used in AVAS and How is This Changing?

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Our research identified several technology trends that are shaping the market for AVAS, these include integration of functional blocks of the module, the industries desire for sound signatures and multiple use cases possible for parts of the AVAS system.

Several components are required for an AVAS system, today fully integrated modules consisting of the 4 core components of an AVAS system – interface, ECU, amplifier and speaker are mostly used. This offers a simple and relatively low-cost way for OEMs to add AVAS and ensure their vehicles are compliant with regulations. Some designs use separate ECU and speaker modules, when needed but this is quite rare in the passenger car market.

As automotive architectures continue to develop and move towards more centralized compute and software defined vehicles, the way that AVAS is implemented is also changing. Most people in the industry expect that more vehicles will integrate AVAS processing into the infotainment system, removing the need for the dedicated ECU. Integrated modules will continue to be the most used type of system, however semi-integrated and dis-integrated modules will grow in popularity as vehicle architecture moves towards more centralized compute platforms. Almost 500 million fully integrated modules are expected to ship from to in total.

The ECU function is expected to be one of first parts of the AVAS system that will be integrated into other parts of the automotive platform. AVAS processing is expected to migrate into the infotainment system SoC. This will enable AVAS to be more closely integrated with other automotive audio functions such as the horn.

Most brands have chosen to use sounds that replicate that of an electric motor, or an ICE engine. OEMs are designing sound signatures that can be used to identify individual brands, working with software companies to develop these sounds and in some cases working with composers as well. Often these sound signatures are being developed alongside active sound design (ASD) for the cabin.

In Tesla started to ship Model 3 and Model Y vehicles with what has been termed a “superhorn”. This combines the horn, alarm and AVAS loudspeaker into 1 system. This is expected to have been a cost reduction effort, reducing the speaker count to 1. Our research suggests that other OEMs are likely to follow suit, combining AVAS with other functions to save cost. Combining with other functional safety features such as a horn makes sense, and it has been suggested that this could make the AVAS system much less likely to be tampered with. The AVAS speaker could also be used as part of an external communication system, where drivers can communicate with people outside the vehicle.

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