Appropriateness of acoustic characteristics on perception of disaster warnings

The appropriateness of acoustic characteristics of speech warnings for natural disasters was examined in this study. Three acoustic parameters (voice gender, speech rate, and pitch) were tested in order to find out the best combination of the acoustics which enhances perceived intelligibility, credibility, and urgency by listeners. A hundred native speakers of Japanese listened to short verbal warnings spoken by a male and a female Japanese speaker with normal pitch, 20 Hz higher, or 20 Hz lower pitch; normal speed, 20% faster, or 20% slower speed. Participants rated each stimulus on 1-to-5-scale. A single effect analysis shows that 1) female voice was perceived with higher credibility and urgency; 2) normal pitch was rated best in the three criteria; and 3) normal speed was perceived best except that faster speed was perceived with higher urgency. A mixed effect analysis found that warnings with the combination of female voice, normal speed, and higher pitch most raised credibility and urgency. Faster speed also raised these two criteria although intelligibility was a little sacrificed. Based on the results, we suggest that disaster warnings with female voice and higher pitch would be effective with the appropriate speaking rate to keep good intelligibility.