Sound Granular Synthesis Method for Science Fiction Sound Quality of Electric Vehicles

Since the powertrain systems of electric vehicles (EVs) lack the traditional engine sound, their NVH performance differs from that of conventional fuel-powered vehicles, making the use of active sound design (ASD) systems increasingly common to provide compensatory sound. With the increasing demand for ASD systems, sci-fi sounds are emerging as a design direction to enhance the acoustic feedback of powertrain systems and to elevate the futuristic and immersive driving experience of vehicles. A method for generating sci-fi soundscapes using a granular synthesis algorithm is proposed in this paper. First, a sci-fi sound is designed based on the characteristics of sci-fi sounds, which serves as the target sound for the synthesis algorithm. Then, it is proposed that sound grains are generated using the adaptive main frequency method, and granular synthesis is achieved through the overlap-and-add (OLA) method. In addition, a method for optimizing the composite cosine window function based on a genetic algorithm is proposed to eliminate the discontinuities caused during OLA synthesis. The optimized window function ensures smoother transitions in the granular synthesis process compared to the traditional window functions, thus improving the overall quality of the sound. Finally, a simulation verification model is constructed, and subjective evaluation experiments are conducted based on the proposed optimization method. The simulation and subjective evaluation results indicate that the sound synthesis algorithm effectively reproduces the target sci-fi sound, and the composite cosine window function, optimized by a genetic algorithm, enhances the auditory smoothness of the synthesized sound grains. This paper proposes a method for powertrain sound compensation, which plays an important role in improving the interior NVH performance of EVs.