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Acceleration Noise Metric for Vehicles with CVT Transmission
Technical Paper
2011-01-0150
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
In recent years, Continuously Variable Transmissions (CVTs) have made significant inroads into passenger cars because of advantages over traditional Automatic Transmissions (ATs) such as improved efficiency, reduced weight and smoother operation. However, from an acceleration sound quality perspective, drivers generally seem to prefer the AT sound over the CVT sound, especially in sub-compact/compact vehicle segment with small displacement engines and cost-conscious sound packaging.
Vehicles equipped with ATs maintain a linear relationship between vehicle speed and engine RPM during wide-open throttle (WOT) acceleration that is dictated by fixed gear ratios. Vehicles with CVTs typically rise rapidly to a high engine RPM (near peak engine torque) and then dwell at a constant engine RPM as the vehicle speed continues to increase by varying CVT pulley ratios. This nonlinear relationship between engine speed and vehicle speed is often perceived negatively by occupants of vehicles with CVTs, particularly those mated to small displacement engines. From an acceleration sound standpoint, occupants experience an extended period of ‘droning’ or ‘humming’ sound; the powertrain sound level and pitch remains relatively constant as the vehicle speed increases during WOT acceleration.
This paper aims to provide a method of quantifying the effects on passenger perception of acceleration noise produced by the modified rpm trajectory of the CVT thereby providing a method of more accurately comparing occupant perception of acceleration noise produced by a CVT equipped vehicle with that of traditional ATs. Subjective ratings of the acceleration noise produced my multiple AT and CVT vehicles were attained and correlated with various metrics. The subjective ratings of acceleration noise showed a strong inverse correlation with the time duration of high loudness level. Application of a sound pressure level / duration tradeoff identified in the literature was examined as a method of improving setting of noise targets for CVTs.
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Citation
Taschuk, E., Kavarana, F., and DeYoung, J., "Acceleration Noise Metric for Vehicles with CVT Transmission," SAE Technical Paper 2011-01-0150, 2011, https://doi.org/10.4271/2011-01-0150.Also In
References
- Kryter, K. D. Pearsons, K. S. “Some Effects of Spectral Content and Duration on Perceived Noise Level” The Journal of the Acoustical Society of America 35 6 866 883 1963
- Little, J. W. Mabry, J. E. “Sound Duration and its effect on judged annoyance” Journal of Sound and Vibration 9 2 247 262 1969
- Yano, T. Asato, K. et al “Effects of duration of repeated impulsive sounds on noisisness” Environment International 16 547 554 1990
- Lee, K.-H. Park, D.-C. Kim, T.-G. Jong-Kim, S. et al. “Characteristics of the Luxury Sound Quality of a Premium Class Passenger Car,” SAE Technical Paper 2009-01-2183 2009 10.4271/2009-01-2183
- Fasti, H Zwicker “Psycho-Acoustics - Facts and Models” Springer Berlin 978-3-540-23159-2 9 243 245 2007