Abstract
The relationship between the rotating movement of a visual image and the periodic pitch modulation of a sound to create subjective congruence was examined using rating experiments. The visual stimulus was a ball continuously rotating along a circular track. The sound stimulus was a periodically ascending and descending pitch modulation of a pure tone. The highest congruence between a moving picture and a sound was obtained when the period of pitch modulation corresponded, or almost corresponded to that of the rotation of the ball. When their periods were obviously different, the degree of congruence decreased. When pitch modulation preceded ball rotation, the congruence was more degraded than that when pitch modulation was delayed. Generally, pitch ascending matched rising image and vice versa. For periodic variation, the vertical correspondence of visual movement and pitch shift was an effective factor to create subjective congruence between ball rotation and pitch modulation. When the directions of the pitch shift and the visual movement were opposite, subjective congruence was lower than when they were the same. The difference between clockwise and counterclockwise rotations of a ball did not affect subjective congruence. Subjective congruence of audio-visual combinations raised the level of their evaluation.
