First reflections of a rigid panel, a rigid concave and convex panel, and a panel with reflection coefficient are reviewed as well as multiple reflections between them. Thus, early reflections in a scale model auditorium were calculated and compared with measured results. The transient response of human hearing system in the form of impulse response with 0.05ms rectangular pulse wave is reviewed. It has the absolutizing process after the linear response. Familiar impact sounds got pair comparison to arrange on the axis of loudness. When each impact sound was convolved with the dB (A) weight and the transient response of our hear-ing system, it was found that the latter convolution showed larger correlation to each loudness. And it was found that the time window of 40ms gives the largest correlation for its loudness among other time windows. The measurement of angle discrimina-tion was done with a 0.05ms rectangular pulse. It exists where the cross correlation of HRTF is 0.98. Acoustical information can be smoothed in this space. If it is expressed in the space using the stereoscopic view, temporal information is also obtained. It can be compared with the given estimation of a concert hall. Acoustical behaviours must be first arranged and established as the linear system on a 0.05ms rectangular pulse, then further steps can be clearer.