A Near-Infrared Spectroscopy Study of Horizontal Vibration and Comfortableness of a Ride

<jats:p>Comfortableness of a ride is an important issue to passengers and drivers in an automobile. It is difficult to quantify comfortableness of a ride because it is affected by the rider’s emotions and physiology. In this paper, we measure brain activity using near-infrared spectroscopy (NIRS) to examine the features of brain activity that occur when a person is feeling vibration. The results obtained in this study may be used to quantify subjective evaluations of comfortableness of a ride. We measured brain activity during vibrations that are uncomfortable and during vibrations that are not uncomfortable. Uncomfortable vibration and vibrations that were not uncomfortable were determined based on sensory evaluations. Results reveal that oxygenated hemoglobin (oxy-Hb) levels in the prefrontal cortex change when feeling vibration. With uncomfortable vibration oxy-Hb levels declined more than with vibration that was not uncomfortable. In addition, we measured brain activity of riders feeling vibration which evaluation vary among subjects. We found that oxy-Hb of the subjects that feel uncomfortable vibration declined in the prefrontal cortex. Therefore, we inferred that the decline of oxy-Hb in the prefrontal cortex is related to feelings of discomfort.</jats:p>