Previous studies have reported that the acoustic features such as the speech rate, fundamental frequency (F0), amplitude, and voice gender are related to emergency perception in speech. However, the most critical factor influencing the emergency perception in speech remains unknown. In this study, we compared influences of three acoustic features (speech rate, F0, and spectral sequence (amplitude)) to determine the acoustic feature that has the most influence on emergency perception in speech. Prior to conducting our experiments, we selected five speech phrases with different level of perceived emergency among various speech phrase spoken by TV casters during real emergencies. We then created synthesized voices by replacing three acoustic features separately among the selected five voices. In experiment 1, we presented these synthesized voices to 10 participants and asked them to evaluate levels of the perceived emergency of each voice by the magnitude estimation method. The results from experiment 1 showed that F0 was most influential on emergency perception. In experiment 2, we examined influences of the three acoustic features on auditory impression related to the perceived emergency by the SD method. The results suggested that emotional effects of some words such as “tense” or/and “rush” were influenced by the fundamental frequency.Previous studies have reported that the acoustic features such as the speech rate, fundamental frequency (F0), amplitude, and voice gender are related to emergency perception in speech. However, the most critical factor influencing the emergency perception in speech remains unknown. In this study, we compared influences of three acoustic features (speech rate, F0, and spectral sequence (amplitude)) to determine the acoustic feature that has the most influence on emergency perception in speech. Prior to conducting our experiments, we selected five speech phrases with different level of perceived emergency among various speech phrase spoken by TV casters during real emergencies. We then created synthesized voices by replacing three acoustic features separately among the selected five voices. In experiment 1, we presented these synthesized voices to 10 participants and asked them to evaluate levels of the perceived emergency of each voice by the magnitude estimation method. The results from experiment 1 show...