Investigating Duration Effects of Emotional Speech Stimuli in a Tonal Language by Using Event-Related Potentials

Studying event-related potentials (ERPs) is considered as an effective method for investigating cerebral mechanisms of processing emotional speech. It has been shown that the amplitudes of ERP components in the cognitive processing of emotional speech are modulated by acoustic characteristics, such as valence and arousal. However, whether the duration of emotional speech stimuli impacts emotion-related cognitive processing remains unclear. To better understand the effect of emotional speech stimulus duration on emotion-related cognitive processing, we explored whether emotional speech ERPs were influenced by the duration of stimuli presented. Specifically, this paper focused on the ERP investigation of different durations (short: 0.50-1.00 s; medium: 1.50-2.00 s; and long: 2.50-3.00 s) of Chinese emotional speech stimuli. Chinese is a typical tonal language, and the stimuli were excerpted from radio plays in order to make emotions more obvious and easier to distinguish. We investigated the three different stages of the emotional speech processing: sensory processing, salience detection, and cognition. During the experiment, participants passively listened to emotional utterances matched for semantics and prosody with four emotions (sadness, anger, happiness, and surprise). Our results showed significant differences in the amplitudes of ERP components for different emotions during short-duration emotional speech stimuli. These findings suggest that shorter duration emotional speech stimuli may be more effective for separating the ERP components representing different emotions (N100, P200, and N300).