Parametric Late Reverberation from Broadband Directional Estimates

Several parametric spatial room impulse response rendering methods use broadband directional estimates, whereby based on sample-by-sample direction-of-arrival estimation, a single channel room impulse response is distributed to multiple loudspeakers. To this end, it has been unclear how such simple parametric processing behaves in the late part of the response. To assess this question, we use simulations and a measurement to show that the commonly applied estimation methods based on the pseudo intensity vector and time difference of arrival estimation do preserve the directional information in the late response. Also, we show that estimated directional differences can be audible under best case conditions. As broadband rendering can sound ‘rough’ or ‘grainy’ for transient input signals due to insufficient pulse density in individual reproduction channels, we use a method to synthesize smooth sounding spatial reverberation. For this, the broadband estimates are used to calculate directional energy envelopes, which are applied to filtered noise sequences. The findings presented here help assessing and improving spatial room impulse response processing methods.