Methods and systems for designing and applying numerically optimized binaural room impulse responses

An audio signal processing device for generating an output binaural signal in response to a set of N audio input signals, wherein the audio signal processing device comprises one or more processing components configured to:

• receive the N audio input signals, wherein each of the N audio input signals corresponds to a spatial location;
• determine N direct response and early reflection binaural room impulse response, BRIR, portions, wherein each direct response and early reflection BRIR portion corresponds to the spatial location of one of the audio input signals;
• determine a late response BRIR portion, wherein a subset of the late response BRIR portion temporally overlaps with subsets of the direct response and early reflection BRIR portions, and wherein the temporally overlapping subset of the late response BRIR portion models the transition from the direct response and early reflection BRIR portions to the late response BRIR portion;
• generate, for each audio input signal, a binaural signal, by processing the audio input signal to apply the corresponding direct response and early reflection BRIR portion;
• generate a first binaural signal by combining the binaural signals for each audio input signal;
• generate a second binaural signal by processing a downmix of the N audio input signals to apply the late response BRIR portion;
• generate the output binaural signal by combining the first binaural signal and the second binaural signal;
• wherein the N audio input signals are time domain audio signals, and the method further comprises transforming the N audio input signals from the time-domain to a filterbank domain to generate N filterbank domain signals, each filterbank domain signal having a plurality of frequency bands.