  Most often, virtual acoustic rendering employs real-time updated room
acoustic simulations to accomplish auralization for a variable listener
perspective. As an alternative, we propose and test a technique to interpolate
room impulse responses, specifically Ambisonic room impulse responses (ARIRs)
available at a grid of spatially distributed receiver perspectives, measured or
simulated in a desired acoustic environment. In particular, we extrapolate a
triplet of neighboring ARIRs to the variable listener perspective, preceding
their linear interpolation. The extrapolation is achieved by decomposing each
ARIR into localized sound events and re-assigning their direction, time, and
level to what could be observed at the listener perspective, with as much
temporal, directional, and perspective context as possible. We propose to
undertake this decomposition in two levels: Peaks in the early ARIRs are
decomposed into jointly localized sound events, based on time differences of
arrival observed in either an ARIR triplet, or all ARIRs observing the direct
sound. Sound events that could not be jointly localized are treated as
residuals whose less precise localization utilizes direction-of-arrival
detection and the estimated time of arrival. For the interpolated rendering,
suitable parameter settings are found by evaluating the proposed method in a
listening experiment, using both measured and simulated ARIR data sets, under
static and time-varying conditions.
