Two new terms for the comparison between acoustical measurements, calculations (ray or image models), and subjective impressions.

The sound energy growth (SEG) curve is a new parameter depicting the growth in sound energy during the first 200–300 ms. An instantaneous sound envelope (ISE) is a new parameter yielding the sound amplitude and arrival time of individual reflections. ISE is especially useful for comparison with calculated reflectograms generated in computer models. ISE shows the contribution of individual reflections to the SEG. The two new terms provide a better comparison between measurements (ISE), calculations (from ray or image computer models), and subjective impressions (SEG) based on energy parameters.