Minimum Sound Testing of Medium- and Heavy-Duty Electric Vehicles

The acoustic performance of seven vehicles was evaluated according to Canadian Motor Vehicle Safety Standard 141 (CMVSS 141), which governs minimum required sound levels for hybrid and electric vehicles with a gross vehicle weight rating (GVWR) of 4536 kg (10,000 lb) or less. To better understand the sound profiles of medium-duty electric vehicles (MDEVs) and heavy-duty electric vehicles (HDEVs), the sound emissions of two light-duty electric vehicles (LDEVs), one MDEV, three HDEVs, including an electric transit bus, and one heavy-duty internal combustion engine (HD ICE) vehicle were compared. The sound emissions of the MDEV and HDEVs were quieter than the HD ICE vehicle and comparable to that of the LDEVs equipped with auxiliary speakers. The MDEV with its auxiliary speaker turned off and all three HDEVs without auxiliary speakers met CMVSS 141 requirements in reverse gear and at speeds of 20 km/h and 30 km/h. The MDEV, though not subject to CMVSS 141, failed to meet the minimum sound requirement at stationary when its auxiliary speaker was deactivated. Similarly, the electric transit bus did not meet sound requirements at stationary and 10 km/h, highlighting the potential of acoustic vehicle alert systems (AVAS) in enhancing the detectability of quiet vehicles.