Comparative Analysis of Noise in Automotive Headrests Under Vibration

Abstract

The study of noise, vibration, and harshness (NVH) in the automotive industry is essential for identifying factors that degrade user comfort, making it important to develop products that are more comfortable, quieter, and of higher quality. In this paper, several automotive headrest models through a combined experimental approach that includes sound pressure level (SPL) measurements under controlled random vibration and operational noise characterization during motorized adjustment. The objective is to assess theinfluence of vibration-induced excitation and to isolate the specific contribution of motorized mechanisms to overall noise emission. Random vibration excitation was considered only in the vertical direction and the test was well controlled inthe 5-200 Hz bandwidth for simulation of cobblestone road conditions. Statistical analysis and perceptual metrics such as loudness were considered. A consistent difference was detectedbetween the headrest models in different bands, where themodel with electronic components and greater interior design complexity for automatic adjustments is noisier than the model without automated mechanisms. The results reveal consistent statistical and perceptual differences between headrests, with the model incorporating electronic components and more complex internal architecture exhibiting higher noise levels across specific frequency bands. These findings identify thefrequency regions most critical for user comfort and establish a methodological framework for evaluating the operational noise of automotive headrests, supporting early-stage design decisions and refinement of motorized mechanisms.