Musical factors, such as short melodies or chords, are widely used for various kinds of auditory signals, in addition to intermittent patterns of sounds. In this study, to show the effect of using chords for auditory signals, the relationship between types of triads (three-note chords) and functional imagery and impression of auditory signals was examined by rating experiments. The experimental results showed the possibility of use of the progression from dominant to tonic chord or their base tone progression as a message of ending. The progression from subdominant to tonic chord also could be used for the message of ending. These sounds also aroused impression of pleasantness and brightness. They are appropriate for auditory signals frequently heard in dairy life. Diminished and minor triad was appropriate for informing danger alarm. They aroused impression of unpleasantness and darkness. Augment triad aroused strong imagery of calling. It also could be used for attracting attention. The present study showed using chords is effective to arouse particular functional imageries and impressions.

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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.

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