Models for evaluating navigational techniques for higher-order ambisonics

Abstract

Models are presented that predict perceived source localization and spectral coloration for the purpose of evaluating navigational techniques for higher-order ambisonics. Previous evaluations typically rely on binaural localization models, which conflate the effects of the navigational technique with those of the adopted ambisonics-to-binaural rendering approach. Moreover, studies on navigation-induced coloration have been largely qualitative. The presented models are applied directly to translated ambisonics impulse responses (i.e., before rendering to binaural) and are validated through listening experiments. Localization is predicted using an extension to a precedence-effect-based localization model. Coloration is predicted using a linear combination of spectral energies and notch-depths in a difference-spectrum between the test and reference signals. For two interpolation-based navigational techniques and a range of translation distances, localization and coloration are also measured subjectively through binaural-synthesis-based listening tests, wherein subjects judge source position for a spatialized sample of speech and rate the induced coloration in pink noise relative to reference signals. The proposed localization model is shown to predict the data with comparable accuracy to that of a binaural localization model and the coloration metrics used are shown to best predict perceived coloration compared to alternative sets of metrics.