Research on minimum sound specifications for hybrid and electric vehicles. U.S. DOT Docket No. NHTSA-2011-0148.

Author(s)
Hastings, A. Guthy, C. Pollard, J.K. & Garay-Vega, L.
Year
Abstract

This report documents research by the National Highway Traffic Safety Administration (NHTSA) to identify ways to develop sound specifications for electric and hybrid vehicles. The research was conducted to support activities related to the implementation of the Pedestrian Safety Enhancement Act of 2010. The Pedestrian Safety Enhancement Act (PSEA) requires NHTSA to conduct a rulemaking to establish a Federal Motor Vehicle Safety Standard (FMVSS) requiring an alert sound for pedestrians to be emitted by all types of motor vehicles that are electric or hybrid (EVs and HVs). The goal is to establish performance requirements for an alert sound that allows blind and other pedestrians to reasonably detect a nearby EV or HV. The alert sound must not require activation by the driver or the pedestrian, and must allow pedestrians to reasonably detect an EV or HV in critical operating scenarios such as, but not limited to, constant speed, accelerating, or decelerating. Sound specifications would include criteria for sounds to be detectable and recognizable as the sound of a motor vehicle in operation. Two concepts to identify potential detectability specifications for alert sounds are explored: (a) minimum sound levels based on psycho-acoustic modelling and detection distances and (b) minimum sound levels based on the sound of internal combustion engine (ICE) vehicles. Potential detectability specifications are discussed in terms of frequency range and minimum sound level for selected one-third octave bands. Also considered is the relative proportion of acoustical energy emitted from a vehicle as a function of direction (directivity). Recognition includes two aspects: recognition that the sound is emanating from a vehicle and recognition of the type of operation that the vehicle is conducting. Potential specifications to aid in recognition are discussed in terms of broadband noise and tones (toneto- noise ratio) and ways to denote changes in vehicle speed (pitch-shifting as a function of vehicle speed). (Author/publisher)

Publication

Library number
20121512 ST [electronic version only]
Source

Washington, D.C., U.S. Department of Transportation DOT, National Highway Traffic Safety Administration NHTSA, 2012, XVI + 90 p., 28 ref.; DTNH22-II-V-00063 / U.S. DOT Docket No. NHTSA-2011-0148

Publication (link)

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