Simplifying head-related transfer function measurements: A system for use in regular rooms based on free head movements

The use of individual head-related transfer functions (HRTFs) can improve the quality of binaural reproduction in virtual acoustic environments. However, measuring individual HRTFs for a large number of directions is usually challenging in terms of time, effort, hardware, and setup requirements. This work presents an HRTF measurement system that can be easily used in regular rooms with a simple measurement setup. The system is based on a stationary loudspeaker and a commercially available tracking system for precise tracking of the subject’s head movements. Subjects can first measure their HRTFs for any number of freely selectable directions. In a second step, they can be guided with the help of an algorithm that suggests additional measurement positions for more uniform spherical coverage. From the resulting measurements on an individual and usually sparse sampling grid, a dense spherical HRTF set is obtained using state-of-the-art spatial upsampling methods. Besides presenting the measurement system, the present work also discusses some of the challenges encountered in designing and developing such a tool.