Based on the outcomes of a European Commission study, proposal to clarify the text and align its provisions with other vehicle sound regulations, especially UN R41, including to replace references to “two wheeled moped” with the term “L1 category vehicles” (and consequently to replace references to “moped” with “vehicle”) and to replace the term “noise” with “sound” (except for references to background noise) throughout the regulation. It proposes improved terminology and definitions, including new ones, improved sound emission testing conditions and procedures. It also introduces sound emission measurement through new testing of in use vehicles in motion.