Using binaural hearing for localization in multimodal virtual environments
Matti Gröhn, Tapio Lokki, Lauri Savioja · 2001
In this article we present the results of localization experiment accomplished in a real virtual room. The spatial audio reproduction methods used in experiment were HRTFs (for headphones), direct loudspeaker reproduction, and vector based amplitude panning. Also the effect of visual stimulus was explored. BACKGROUND Virtual environment is an interactive immersive mul-tisensory 3-D synthetic environment; it uses position-tracking and real-time update of visual, auditory, and other displays (e.g., tactile). Currently spatial audio has been mostly used for sense of presence. There are four common tasks in immersive visualiza-tion (localization, orientation, navigation, and data repre-sentation). In this research localization is defined as user ability to define direction and distance of the target. The other tasks and more detailed description of this research project as a whole is in article [1]. In this research we are comparing head-tracked binau-ral headphone reproduction (using HRTFs), direct loud-speaker reproduction, and vector based amplitude pan-ning (VBAP) using loudspeakers [2]. The task of the user is to point to direction of the perceived sound source, and click the button of a interaction device. According to Dje-lani et al. [3] pointing is an appropriate method for local-ization experiments. In our test the user can freely move inside the virtual environment (as they typically do while they are using some application). LOCALIZATION TEST According to Blauert [4] the absolute lower limit for localization accuracy in front is one degree. In our exper-iment we have measured the localization accuracy inside a real virtual room, where there are many factors, that de-crease the localization accuracy. For example, we didn’t use individualized HRTF’s, because they typically are not available. Instead, HRTF’s were measured a from dummy head. On the other hand, the screens and room reverber-ation will deteriorate loudspeaker reproduction accuracy. Test environment Localization tests has been made in our virtual room