Near-field Head-Related Transfer Functions (HRTFs) depend on both source direction (azimuth/elevation) and distance. The acquisition procedure for near-field HRTF data on a dense spatial grid is time-consuming and prone to measurement error, therefore, existing databases only cover a few discrete source distances. Coming from the fact that fast, continuous acquisition of HRTFs with a high azimuthal resolution has been enabled via the usage of LMS(Least Mean Square)-type adaptive filtering methods, in this paper, we expand the application of the adaptive filtering approach to measure near-field HRTFs while continuously varying the source distance. We developed and validated a novel measurement setup that allows the acquisition of near-field HRTFs for source distances from 20 cm to 120 cm with one recording. We then evaluated the measurement accuracy by analyzing the estimation error from the adaptive filtering algorithm and the objective features of HRTF related to near-field binaural rendering.
http://www.aes.org/e-lib/browse.cfm?elib=21688
