Investigating measurement uncertainties of head-related transferfunctions using pole-zero analysis
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Bachelor Thesis of Zhu, Chendi
A head-related transfer function(HRTF) describes the filtering process of sound waves arriving at ears through reflection, diffraction, and resonances. The HRTFs possess a direction-dependent and a direction-independent part. A fast measurement system uses an array of 64 loudspeakers, which are optimized in order to reduce the potential influence on the measurement. However, some factors still influence the individual measurement of HRTFs, e.g. movement of subjects.In this work, a new method is developed in order to investigate the measurement system, i.e.the experimental error caused by repeated measurements. The key point is the analysis on the changes of HRTF’s frequency spectrum for same directions by repetitive measurement. Pole-zero analysis is applied in order to approximate the maxima and the minima of the frequency spectrum, which minimizes the logarithmic difference between original HRTFs and reconstructed HRTFs. A new distance metric is introduced to assess the difference between HRTF measurements, based on the relative deviation of pole and zero positions. First investigations are performed on a series of repeated HRTF measurements.