Title: 3D Audio Reproduction via Headrest Equipped with Loudspeakers—Investigations on Acoustical Design Criteria
text: This paper focuses on the analysis and evaluation of acoustical design criteria to produce a plausible 3D sound field solely via headrest with integrated loudspeakers at the driver/passenger seats in the car cabin. Existing audio systems in cars utilize several distributed loudspeakers to support passengers with sound. Such configurations suffer from individual 3D audio information at each position. Therefore, we present a convincing minimal setup focusing sound solely at the passenger’s ears. The design itself plays a critical role for the optimal reproduction and control of a sound field for a specific 3D audio application. Moreover, the design facilitates the 3D audio reproduction of common channel-based, scene-based, and object-based audio formats. In addition, 3D audio reproduction enables to represent warnings regarding monitoring of the vehicle status (e.g.: seat belts, direction indicator, open doors, luggage compartment) in spatial accordance. Furthermore, individual sound zones enable superior in-car communication between seats regardless of the current driving situation. An often overlooked topic is the acoustical privacy of in-car systems towards the exterior especially during telephony which is also tackled by the presented design as a by-product. We present how the structural shape, the assembly and alignment of the loudspeakers affects the frequency response, the effective sound pressure levels at the passenger’s ears, the inter-aural crosstalk, and the crosstalk to other seats. We further show that person affects the sound field by movements and therefore can change the overall performance. Finally, we present our approach for 3D audio reproduction for the car cabin schematically.