With　the　development　of　3D　audio,　distance　rendering　in　multi-channel　spatial　audio　becomes　a　hot　topic　of　great　interest.　In　this　paper,　the　directional-to-diffuse　energy　ratio　(DDR),　a　novel　relative　distance　cue,　is　presented　based　on　Fast　Independent　Components　Analysis　(FastICA).　DDR　is　used　to　trace　the　relative　distance　of　recreated　sound　image,　by　extracting　the　energy　ratio　of　the　directional　component　and　the　diffuse　component　in　multi-channel　audio　signal.　Combined　the　human　auditory　perception,　a　mapping　relationship　is　discussed　between　DDR　and　relative　distance.　According　to　the　subjective　comparison,　the　estimated　relative　distance　could　validly　reveal　the　perceived　relative　distance.　©　2014　IEEE.