Spatial sound resolution of an interpolated HRIR library

The paper evaluates the human directional resolution of virtual sound sources synthesised with the aid of a generalised head related impulse response (HRIR) library, i.e., an HRIR library measured using a dummy head and torso. The original HRIR set is first expanded using linear interpolation, and then directional resolution measurements are performed for playback through headphones. These results are compared to the results obtained using loudspeakers as sound sources in an anechoic chamber. Directional resolution is the ability of listeners to distinguish two closely-spaced sound sources alternately playing the same signal. Experiments show that two sound sources with insufficient spacing appear as a single source to the listener. Directional resolution for small azimuth changes is relatively high for both virtual and real sound sources. Most test subjects have no problem resolving two sound sources only 5° apart. Compared to real sound sources, detecting changes in elevation of virtual sound sources is much less accurate, which may be the main drawback of using a generalised HRIR library.