Prominence of tones in electric vehicle interior noise

Abstract

The rapid increase of various types of electric vehicles introduced creates new challenges also in respect to noise control and sound quality. With the absence of acoustic emissions from an operating internal combustion engine, the presence of high pitched tonal components from the electric traction motor can be pronounced in many driving conditions. In order to fulfill the customer’s expectations of interior acoustic comfort, further knowledge needs to be gained about the perception of tonal components appearing in a mix of random noise from wind and tires. This paper presents a study on the relationship between the psychoacoustic metric prominence ratio (PR) and the threshold of detecting the tones and also the perceived annoyance for both constant speed and acceleration in a pure electric vehicle. The listening test results reveal that below 800 Hz, a higher PR value is required for audibility compared to tones above 2.5 kHz. For all driving conditions, the perceived annoyance was relatively low with small differences between the frequency ranges for the low audibility stimuli (PR≤2 dB). With higher audibility (PR≥3 dB), the perceived annoyance was significantly increased for frequencies above 5 kHz compared to frequencies below 800 Hz for the constant speed cases. The acceleration cases yielded similar conclusions. The findings are intended to support in the requirement specification process for sounds in electric vehicles.