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Sound externalization using dynamic cue
Listening to the sound with headphones using portable multimedia devices has become common lately. If the sound is not properly postprocessed by headphone designated algorithm, it is likely to be localized inside the head (sound internalization), making the stereo image unnaturally lateralized between the ears and generally narrow. For realistic audio rendering, ¡®out-of-head¡¯ localization (sound externalization) is needed.

Figure 1. Concept of sound externalization

Most of existing sound externalization methods are based on HRTF filter and reverberator to apply sound transfer characteristics and reflection effect, but externalization performance is not enough for ¡®out-of-head¡¯ localization.

In this research, compensating the change of sound transfer characteristics with head motion (dynamic cue) is adopted and the externalization performance was analyzed to confirm the influence of dynamic cue. For that, HRTF filter and reverberator are updated with the head motion in real time and the sound source is localized in specific position relative to the orientation of the listener.

Figure 2. Sound externalization using dynamic cue

Feasibility test results demonstrated that, using dynamic cue with reverberator improve the performance of existing method, but the influence of dynamic cue is less than that of reverberation cue.