What is the ECE R138 AVAS sound regulation about electric and hybrid vehicles ?

ECE R138 / AVAS is aimed to prevent vulnerable people on the road (children, bikers, elderly, visually impaired people and pedestrian potentially distracted) from the danger raised by quiet running vehicles. SESALY offers sound equipments for bus and coach able to answer this new standard.
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What is ECE R138 regulation ?

According to this regulation, from the 1st of July 2019 onwards and at the latest on the 1st of July 2021, all new licensed electric and hybrid vehicles that do not reach the minimum required sound level must install sound alert devices called AVAS (Acoustic Vehicle Audible System) in order to simulate the same sound level as a vehicle with thermal engine.

Which vehicles are concerned by the AVAS system ?

R138 is applied to all electric and hybrid vehicules of M & N1 categories, which can circulate normaly and in forward direction with a motor speed selection and on which there is no internal operating engine combustion.

What does the AVAS sound consist in ?

The AVAS (Acoustic Vehicle Alert System) is a sound able to indicate the presence of an electric or hybrid vehicle operating at a speed from 0 to 20 km/hour (12.5 miles/h). This sound can reach from 56 to 75 decibels. It has to vary depending on the vehicle accelera-tion from 0 to 20 km/hour (12.5 miles/h). Above 20 km/hour, the AVAS is not compulsary as we can hear properly rolling noises.

What does the AVAS regulation consist in ?

The AVAS regulation concerns vehicles, not the equipments. In order to comply with AVAS regulation, the vehicle must answer 2 key points quantified in sound level (dB) & on a frequency range (Hz) :

  • To reach the required global sound level (ZdBmin). The vehicle will have to answer to vehicle approval constraints by compiling its own rolling sound (XdB), completed by the AVAS sound (YdB) and adjusted by the installation type in the vehicle (▲dB).The formula ZdB = XdB + YdB – ▲dB will therefore be applied.
  • To provide a precise answer to garanty a defined frequency / speed range

What are risks incurred if this regulation is not applied ?

Electric and hybrid vehicles that natively do not reach the required sound levels are imperatively submitted to R138 regulation.


Vignal Group manufactures multifonction solutions able to meet the ECE R138 / AVAS regulations.


You want to know everything on SESA Tunes, the AVAS / ECE R138 sound creation by SESALY, in less than 2 minutes ?

SESA Tunes AVAS range is composed of two products :

SESA Tunes AVAS range is composed of two products :
  • SESA Tunes Advanced is a programmed and intelligent acoustic alert for hybrid or electric buses and coaches able to diffuse the 3 majors exterior warning sounds: the AVAS R138 sound (Acoustic Vehicle Audible System), the pedestrian gong and the reverse alarm sounds.
  • SESA Tunes Premium is the first interior and exterior warning sounds box for electric and hybrid buses and coaches able to diffuse & program 1 AVAS R138 sound + 12 other sounds with intelligence inside (CAN reading is included).