Are there systematic movements of poles/zeros with sound source location for pole/zero models of acoustic directional transfer functions?

Abstract

Humans and animals locate sound sources using three main acoustical cues: Interaural time (ITD) and level (ILD) differences and monaural spectral shape cues. The cues are generated by the spatial‐ and frequency‐dependent filtering of the propagating sound waves by the torso, head, and external ears. These acoustic transformations can be captured in measurements of the directional transfer functions (DTFs), the directional components of the head related transfer functions (HRTFs). A set of DTFs can be used to create a virtual auditory environment by presenting over headphones arbitrary sounds filtered with DTFs. DTFs are generally measured at finite locations in azimuth and elevation, so models are needed to synthesize DTFs for source locations not measured. Here, we investigated the use of different pole/zero models with different orders to model DTFs measured in humans and cats. With models that successfully characterized the DTFs with little error, we examined the systematic movements of the poles/zeros in the unit circle with changes in source azimuth and elevation. The ultimate goal of this research is to find a simple relationship between the movements of the poles/zeros with source location. [NIH Grant No. R01‐DC6865.]