This report documents research conducted to identify potential methods of developing specification for vehicle sounds (audible countermeasures), for use in electric vehicles (EV), plug-in hybrid electric vehicles (PHEV) or hybrid electric vehicles (HEV) operating in electric mode. The research focused on developing objective specifications for detectability using sound pressure levels (SPLs) and spectral profile characteristics. The feasibility of objectively specifying other aspects of sound quality for the purpose of predicting recognizability was explored.
This research was funded by the National Highway and Traffic Safety Administration’s (NHTSA) Office of Human-Vehicle Performance Research and is a follow-on to NHTSA’s Phase 1 research, which initially studied the issue of Quieter Cars. The Volpe National Transportation Systems Center (Volpe Center) of the U.S. Department of Transportation’s Research and Innovative Technology Administration (RITA) completed this research under an Inter-Agency Agreement (IAA) with NHTSA.
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