Subjective evaluation of a low-order parametric filter model of the pinna for binaural sound rendering

The acoustic effects undergone by a sound wave on its way from the source to the listener's ears are summarized in a specific transfer function (Head-Related Transfer Function, HRTF), whose contribution given by the pinna alone is known as PRTF (Pinna-Related Transfer Function). The PRTF of a listener can be approximated with a specific synthetic model that simulates the main crests and troughs of its magnitude response through low-order peak and notch filters, the parameters of which are only partially related to the anthropometry of the listener himself. Starting from this model, the paper describes a psychoacoustic experiment designed with the aim of testing the accuracy of the model - in terms of vertical localization - for sound sources on the median plane and for different combinations of those parameters not related to anthropometry. Results on twelve experimental subjects suggest which combination of parameters offers a lower localization error with respect to the target elevation of the sound source, thus obtaining useful information for the design of structural models for binaural sound synthesis.