Low order all-pole and all-zero models of human and cat directional transfer functions.

Abstract

Directional transfer functions (DTFs), the directional components of head related transfer functions, are generally measured at finite locations in azimuth and elevation. Thus models are needed to synthesize DTFs at finer spatial resolution than the measured data to create complete virtual auditory displays. Here, minimum-phase all-pole and all-zero models were used for modeling both human and cat DTFs. For the human DTFs, model orders were chosen to achieve specific objective error criteria published in previous studies that were based on subjective listening tests. Because subjective listening tests are not always feasible in animals, objective methods must be used to assess the quality of the DTF reconstructions. Here, the same error criteria reported in subjective tests of human DTF reconstructions were used to constrain models of cat DTFs based on the assumption that if humans cannot discriminate reconstructed versus empirical DTFs for a given objective reconstruction error, then cats will not be able to either provided the reconstruction error is held below that criteria. All-pole and all-zero models of orders as low as 25 were able to model DTFs with errors comparable to previous research findings and preserve the main spectral features in both human and cat DTFs. [Work supported by NIH Grant No. R01-DC6865.]