This study was conducted in conjunction with the University of California, Davis, to evaluate candidate test procedures for assessing the detectability of quiet vehicles by the blind community. The SAE Pass-by noise test is clearly not applicable to this situation, as it is conducted at speed 50 kph and higher, therefore new test procedures needed to be investigated by the government and the industry. A jury study at the National Federation of the Blind California conference was performed. A combustion engine vehicle was converted into an electric vehicle and speakers were attached at each corner. Blind volunteers from the conference participated in the study where the vehicle was driven past them three times under different conditions. The subject raised their hand when they heard the vehicle and the distances from the subject were noted. The results of this study indicate that the loss of normal combustion engine noises may significantly affect the ability of blind individuals to distinguish approaching vehicles and that a substitute sound generation mechanism may be required to reverse this risk.
Reference: SAE paper 2009-01-2189 (under Technical Library)