Visualizations based on a diffusion equation model are presented for transient sound energy in a two coupled-room system. Animations of time-dependent energy flow directions visualize the energy flows across coupled spaces. Particularly, the sound energy feedback is identified through the energy flow direction changes when the coupled room is more reverberant than the main room. This study reveals a "reversal" characteristic of energy flow directions which seems to be dependent on the size and the location of the aperture. Through Bayesian decay analysis and sound energy flow modeling, this work also discloses that the turning point on double-sloped energy decay is highly correlated to the time instant when the energy flow direction reverses.