Distance encoding via headphones

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A couple of Head Related Transfer Functions (HRTF) exists with an angle-resolution of 5 degrees azimuth and 10 degrees elevation. By performing measurements for one loudspeaker at a distance of 1.4 m to a mock-up head the distance-perception of reproduction through one of these HRTF-pairs is given. By combination of multiple Transfer Functions the distance of a virtual (primary) sound source can be varied.

The calculation of the signals of the secondary sources for the desired position of the primary source is done by wave field synthesis (WFS). Adequate filtering procedures and spatial distribution of the primary signal are followed by coding to ambisonic domain which gives possibilities to vary time as well as the position of the virtual source in azimuth and elevation. In Ambisonic domain the resulting sonic field is decoded to the virtual loudspeakers. From these virtual loudspeaker signals and after filtering with appropriate HRTF´s the output (headphone) signals are obtained.

Primary goal of this project is the positioning of the virtual sources in various distances with focus on the difference of given distance and perceived distance.

The influence of the distance-perception is to be investigated depending on different filter parameters.