  The presentation of a moving tactile stimulus to a person's forearm evokes a
pleasant sensation. The speed, intensity, and contact area of the strokes
should be systematically changed to evaluate the relationship between
pleasantness and tactile stimuli in more detail. Studies have examined the
relationship between stroking stimulation and pleasant sensations using
airborne ultrasound tactile displays. The ultrasound-based method has the
advantage of reproducible control of the speed, intensity, and contact area of
the stimulus. In this study, we prepared new stimuli focusing on the modulation
methods and the contact area and aimed to clarify their relationship with
pleasantness in more detail. Evaluating subjective sensations, such as
pleasantness, numerically and consistently is challenging, warranting
evaluation based on comparison. We propose a stimulus evaluation method that
combines rough evaluation using Likert scales, detailed evaluation using
pairwise comparisons, and quantification of comparison data using the
Bradley--Terry model. As a result, we confirmed that the stimulus using lateral
modulation and that with a large contact area used in this study were more
pleasant than the conventional stimulus for six out of ten participants.
