Bimodal Displays Improve Speech Comprehension in Environments with Multiple Speakers

Attending to a single voice when multiple voices are present is a challenging but common occurrence. An experiment was conducted to determine (a) whether presenting a video display of the target speaker aided speech comprehension in an environment with competing voices, and (b) whether the “ventriloquism effect” could be used to enhance comprehension, as found by Driver (1996), using ecologically valid stimuli. Participants listened for target words from videos of an actress reading while simultaneously ignoring the voices of 2 to 4 different actresses. Target-word detection declined as participants had to ignore more distracting voices; however, this decline was reduced when a video display of the target speaker was provided. Neither a signal-detection analysis of performance data nor a gaze-contingent analysis revealed a ventriloquism effect. Providing a video display of a speaker when competing voices are present improves comprehension, but obtaining the ventriloquism effect appears elusive in naturalistic circumstances. Actual or potential applications of this research include those circumstances in which a listener must filter a relevant stream of speech from among multiple, competing voices, such as air traffic control and military environments.