Hybrid powertrain vehicles inherently create discontinuous sounds during operation. The discontinuous noise created from the electrical motors during transition states are undesirable since they can create tones that do not correlate with the dynamics of the vehicle. The audible level of these motor whines and discontinuous tones can be reduced via common noise abatement techniques or reducing the amount of regeneration braking. One electronic solution which does not affect mass or fuel economy is Masking Sound Enhancement (MSE). MSE is an algorithm that uses the infotainment system to mask the naturally occurring discontinuous hybrid drive unit and driveline tones. MSE enables a variety of benefits, such as more aggressive regenerative braking strategies which yield higher levels of fuel economy and results in a more pleasing interior vehicle powertrain sound. This paper will discuss the techniques and signals used to implement MSE in a hybrid powertrain equipped vehicle. MSE utilizes powertrain signals from the vehicle bus to determine which harmonics need to be veiled and at what output level. By-enhancing and complementing the naturally occurring electric propulsion sounds, it's possible to create a more continuous and rich hybrid powertrain sound through the hybrid transition states. As MSE is adding noise to improve the overall sound in the vehicle, this feature can also be utilized to make the vehicle sound heartier and more refined for acceleration or deceleration events while simultaneously masking unwanted tones. The MSE concepts discussed in this paper are covered under US patent 9237399.
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