Virtual navigation within a three-dimensional ambisonics-encoded sound field (sound field that has been decomposed into spherical harmonics) enables a listener to explore with 6 degrees of freedom an acoustic space. This allows for experiencing a spatially- and tonally-accurate perception of the sound field. The authors propose and characterize through numerical simulations an interpolation-based method for virtual navigation, wherein a subset of microphones is parametrically determined to ensure that the region of validity restriction is not violated. An existing alternative method, in which navigation is performed by computing a weighted average of the higher-order ambisonics (HOA) signals from each microphone, was shown to incur spectral distortions due to comb-filtering and localization errors The proposed method employs knowledge of the locations of any near-field sources in order to determine which HOA microphones are valid for use in the navigation calculation as a function of the desired listening position. Additionally, at low frequencies, the proposed method applies a matrix of regularized least-squares inverse filters to estimate the ambisonics signals at the listening position, while at high frequencies, the weighted average method is employed. The numerical simulations were validated against experimental measurements, which showed that the observed discrepancies, and therefore the fidelity of the simulations, do not depend significantly on the navigational method, microphone spacing, or source position.
Download Now (1.1 MB)