Évaluer l'apport du binaural dans une application mobile audiovisuelle

Abstract : In recent years, smartphone and tablet global performances have been increased significantly (CPU, screen resolution, webcams, etc.). This can be particularly observed with video quality of mobile media services, such as video streaming applications, or interactive applications (e.g., video games). However, these evolutions barely go with the integration of high quality sound restitution systems. Beside these evolutions though, new technologies related to spatialized sound on headphones have been developed, namely the binaural restitution model, using HRTF (Head Related Transfer Functions) filters.In this thesis, we assess the potential contribution of the binaural technology to enhance the quality of experience of an audiovisual mobile application. A part of our work has been dedicated to define what is an “audiovisual mobile application”, what kind of application could be fruitfully experienced with a binaural sound, and among those applications which one could lead to a comparative experiment with and without binaural.In a first place, the coupling of a binaural sound with a mobile-rendered visual tackles a question related to perception: how to spatially arrange a virtual scene whose sound can be spread all around the user, while its visual is limited to a very small space? We propose an experiment in these conditions to study how far a sound and a visual can be moved apart without breaking their perceptual fusion. The results reveal a strong tolerance of subjects to spatial discrepancies between the two modalities. Notably, the absence or presence of individualization for the HRTF filters, and a large separation in elevation between sound and visual don’t seem to affect the perception. Besides, subjects consider the virtual scene as if they were projected inside, at the camera’s position, no matter what distance to the phone they sit. All these results suggest that an association between a binaural sound and a visual on a smartphone could be used by the general public.In the second part, we address the main question of the thesis, i.e., the contribution of binaural, and we conduct an experiment in a realistic context of use. Thirty subjects play an Infinite Runner video game in their daily lives. The game was developed for the occasion in two versions, a monophonic one and a binaural one. The experiment lasts five weeks, at a rate of two sessions per day, which relates to a protocol known as the “Experience Sampling Method”. We collect at each session notes of immersion, memorization and performance, and compare the notes between the monophonic sessions and the binaural ones. Results indicate a significantly better immersion in the binaural sessions. No effect of sound rendering was found for memorization and performance. Beyond the contribution of the binaural, we discuss about the protocol, the validity of the collected data, and oppose theoretical considerations to practical feasibility.
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Submitted on : Wednesday, October 2, 2019 - 10:58:08 AM
Last modification on : Friday, October 4, 2019 - 1:55:31 AM

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Julian Moreira. Évaluer l'apport du binaural dans une application mobile audiovisuelle. Acoustique [physics.class-ph]. Conservatoire national des arts et metiers - CNAM, 2019. Français. ⟨NNT : 2019CNAM1243⟩. ⟨tel-02303292⟩

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