Designing acoustic and non-acoustic parameters of synthesized speech warnings to control perceived urgency

To refine synthesized speech warning systems with urgency mapping, various kinds of acoustic and non-acoustic parameters were explored, and the relationship between the parameters and the subjectively perceived urgency was investigated through a series of experiments. The results showed that the speech rate, average fundamental frequency (F0), warning message, message format, gender of voice, and interval between warning messages strongly influence the subjectively perceived urgency of synthesized voice warnings. For the three quantitative parameters: speech rate, average F0, and interval between warning messages, the results showed that it is possible to use psychophysical techniques (Stevens's power law) to quantify the effects of acoustic changes on perceived urgency.