In Japan, vehicle horns have been used as a means of communication between drivers, and frequently aroused psychological negative reactions in hearers. If horn sounds have acoustic features of speech, they possibly help communication between drivers, and improve hearers negative impressions. To investigate such hypotheses, psychoacoustical experiments were conducted using synthesized horn sounds with acoustic characteristics of Japanese speech abunai, which implies a dangerous situation. Spectral features and temporal envelopes were extracted from the speech stimulus and the similar one with swapped syllables, and were reflected in horn sounds. Two experiments were carried out to examine the effects of acoustic characteristics of horn sounds on the perceived quality and interpretations of the intention behind another drivers horn use. Stimuli with spectral characteristics of the speech and those of swapped syllables were evaluated as being less unpleasant and more safe than the original horn sound. On the other hand, many responses of caution and danger were obtained for the stimulus with spectral characteristics of the speech. Results suggested that the horn sound with spectral characteristics of the speech improved from the original horn sound in the perceived quality, and correctly communicated the intention behind another drivers horn use.