What does it cover?
UN R138 addresses reduced audibility of M- and N-category electrified vehicles able to move without the combustion engine operating. It considers external vehicle sound and the Acoustic Vehicle Alerting System (AVAS). Natural vehicle sound is distinguished from synthetic warning sound.
Who is it for?
For vehicle, engine and powertrain manufacturers and measurement, testing and approval teams.
Which subjects are addressed?
- Audibility of M and N electrified vehicles
- AVAS sound characteristics
- Natural sound and warning sound
Common question
Does R138 concern sound comfort inside the cabin?
No. Its subject is external acoustic information to pedestrians and other road users about the vehicle’s presence and operation. Cabin sound comfort is a different assessment.
Published RegsUP edition
This page is tied to the published RegsUP working edition below; it is not an official consolidated text.
RegsUP record title: R138 — UN Regulation No. 138
Working series: 02 · Included supplement: 1
RegsUP edition publication date:
This is the RegsUP publication decision date, not the date the regulation entered into force.