Interior and Motorbay Sound Quality Evaluation of Full Electric and Hybrid-Electric Vehicles based on Psychoacoustics

The different techniques for the evaluation of sound quality are investigated for wide-open-throttle sound stimuli from the interior and motor-bay sound of electric vehicles. Five standard production electric vehicles and one hybrid electric vehicle was tested in Germany and their sound signatures are evaluated in combination with three modified sound signatures. Psychoacoustic metrics such as Sound Power Level (SPL), Third Octave analysis are compared to Zwicker Loudness and Specific Loudness analyses. The Zwicker and Specific Loudness techniques emphasize the subjective aspects of loudness more distinctly compared to the traditional amplitude or magnitude based loudness. Additional sound quality metrics such as Sharpness, Roughness and Impulsiveness are correlated with subjective bi-polar semantics and a rating of sound satisfaction. The Zwicker Loudness reveals a greater variance within the measured data set and thus establishes a platform for distinguishing between similar vehicle sounds. The correlations between objective and subjective preferences provide a framework for future sound concept design of electric vehicles with regards to customer satisfaction.