The Journal of the Acoustical Society of KoreaISSN:1225-4428(Print) 2287-3775(Online)한국음향학회

In recent years, the automotive industry has increasingly adopted large displays to replace physical buttons, drawing attention to touch and haptic technologies. While low-frequency haptic technologies, particularly those based on the bending wave principle, are widely used, they have been criticized for generating noise. This noise arises because vibrations from the display radiate sound, causing discomfort. In this study, we explored a method to implement haptic feedback through vibration motors upon touch, maximizing vibration at the touch point while minimizing overall noise. To achieve this, we defined a new index called the Haptic Noise Index (HNI) to select optimal frequencies, identifying the frequency with the lowest HNI. The HNI is defined as the ratio of vibration at the touch point to the Equivalent Radiated Power (ERP). Additionally, we adjusted the phase of the vibration motors, treated each motor’s vibration contribution as a design variable, and used HNI as the objective function for optimization. By applying this approach, we successfully reduced noise at specific touch locations. The optimization was performed using an Sequential Quadratic Programming (SQP) algorithm. As a result, we achieved noise reduction of over 10 dB compared to signals without the application of this method.