Fundamental psychoacoustical investigations on the perception of projected sound sources

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Modern car, multimedia, and smart-home applications require the reproduction of sound from various directions (e.g., for warning or information signals). Due to the high technical effort or the spatial conditions, a sound reinforcement with distributed loudspeakers might not be possible in many of such situations. One solution is the projection of sound sources on reflective boundaries, e.g., room boundaries. Therefore, highly focused sound sources are necessary. In this case the perceived direction of the auditory event changes from the direction of the real source to the direction of the projected source. A flexible way for creating focusedsound beams is the use of miniature loudspeaker arrays. They can be fully and inconspicuously integrated into existing structures, e.g., enclosures of electrical devices, pieces of furniture, or walls. However, due to their length and the inter speaker distance, loudspeaker arrays have a highly frequency dependent directivity. The exact structure of this directivity determines the perception of projected sound sources. If the sound beam is not focused sufficiently, a significant part of the sound will be radiated directly from the array to the user. Due to the precedence effect, this sound will suppress the perception of the later arriving sound from the projected source. An auditory event at the direction of the array occurs. If the sound beam is highly focused, only marginal directly radiated sound remains. Due to backwardmasking, the perception of this sound can be suppressed by the later arriving sound from the projected source. An auditory event at the direction of the projected source occurs. Pilot studies have shown that therefore the focusing performance of the array has not to be constant within the audio frequency range. The objective of this research project is an insight into theperception of projected sound sources by means of basic research on backward masking. An integral conception of playback systems, which regards the perception of the user in addition to technical aspects, provides new levels of freedom in design. This leads to more flexible and robust systems with a better perceived playback quality. Furthermore, a specific stimulation of the tactile modality can relieve the overloaded auditory modality in a scenario with projected sound sources. This extends the flexibility in the projection of sound sources for low frequencies. Initially, the involved phenomena of the auditory and audio-tactile perception will be investigated in studies with healthy volunteers. Subsequently, a prototype will be developed using the new perception based approach. It will be investigated in a final study, how the perception based development approach improves the perceived quality of the projection of sound sources in a real life environment.