Electric vehicle additive sounds: Detection results from an outdoor test for sixteen participants

Abstract

Electric vehicles are significantly quieter than standard internal combustion engine vehicles. Although this is a benefit to the acoustic soundscape, it presents a safety concern, particularly to the vision impaired. Because of this, governments around the world have mandated that artificial sounds be added to electric vehicles in order to improve pedestrian safety. In the United States, these regulations are embodied in a National Highway Transportation Safety Administration document, FMVSS-141. This document provides guidance on the 1/3 octave-band frequency content, overall SPL, and measurement procedures that must be followed for a vehicle to be certified. This talk will present the results of a listener test with 16 participants who pressed a button upon detection of an approaching vehicle equipped with a FMVSS-141 compliant additive sound. Results are presented at probability of detection versus distance. This provides a unique view of the effectiveness of these sounds and additional aspects of this problem such as additive sound contribution to noise pollution and listener false alarm rates. Lastly, the talk will cover difficulties with this type of outdoor testing and recommendations for conducting them in a virtual environment.