Influence of diagetic and non diegetic sound in films
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Over the past decade, many studies have been made to explore the influence between the sound of a film and the eye gaze. Most of them showed a significant influence of the sound in the eye movements but no study has been made differentiating the effect of diegetic sound from non- diegetic sound. The first one is the sound belonging to the scene, all the sound that a character inside the film could hear (dialogues, footsteps, car engine, phone ringing), and the non-diegetic sounds are the ones that have been added in postproduction and don not belong to the world of the film (music, sound effects, narrator). The aim of this study is to determine the effects of each type of sound in visual perception. In order to do so, an eye-tracking experiment was done. 

Participants: Twelve participants took the experiment (seven men and five women, aged between 20 and 56).

Procedure: Each participant watched the same video but each one with one auditory modality out of four different ones (silent, only diegetic sound, only non-diegetic sound, and complete sound). An eye-tracker was used to record the gaze. 

Results and discussion: No significant differences were found regarding fixation and saccade rate and durations. A change in auditory information affects the human gaze, when the information is linked to a visual event in the video, this means for diegetic sounds. More dispersion was found in the silent modality than the other modalities.