  Although 360\textdegree{} cameras ease the capture of panoramic footage, it
remains challenging to add realistic 360\textdegree{} audio that blends into
the captured scene and is synchronized with the camera motion. We present a
method for adding scene-aware spatial audio to 360\textdegree{} videos in
typical indoor scenes, using only a conventional mono-channel microphone and a
speaker. We observe that the late reverberation of a room's impulse response is
usually diffuse spatially and directionally. Exploiting this fact, we propose a
method that synthesizes the directional impulse response between any source and
listening locations by combining a synthesized early reverberation part and a
measured late reverberation tail. The early reverberation is simulated using a
geometric acoustic simulation and then enhanced using a frequency modulation
method to capture room resonances. The late reverberation is extracted from a
recorded impulse response, with a carefully chosen time duration that separates
out the late reverberation from the early reverberation. In our validations, we
show that our synthesized spatial audio matches closely with recordings using
ambisonic microphones. Lastly, we demonstrate the strength of our method in
several applications.
