Influence of visual cues on head and eye movements during listening tasks in multi-talker audiovisual environments with animated characters

Recent studies of hearing aid benefits indicate that head movement behavior influences performance. To systematically assess these effects, movement behavior must be measured in realistic communication conditions. For this, the use of virtual audiovisual environments with animated characters as visual stimuli has been proposed. It is unclear, however, how these animations influence the head- and eye-movement behavior of subjects. Here, two listening tasks were carried out with a group of 14 young normal hearing subjects to investigate the influence of visual cues on head- and eye-movement behavior; on combined localization and speech intelligibility task performance; as well as on perceived speech intelligibility, perceived listening effort and the general impression of the audiovisual environments. Animated characters with different lip-syncing and gaze patterns were compared to an audio-only condition and to a video of real persons. Results show that movement behavior, task performance, and perception were all influenced by visual cues. The movement behavior of young normal hearing listeners in animation conditions with lip-syncing was similar to that in the video condition. These results in young normal hearing listeners are a first step towards using the animated characters to assess the influence of head movement behavior on hearing aid performance.