This is another perspective on the significance of reverberation time and early-decay time, and the relationship between the two.
I must preface the following with the acknowledgment that most on the SAC Email Group have interests that focus on applications of sound reinforcement. This text will widen the discussion to include acoustical sources – however, it is germane to a common dialog about how we as humans interpret sound, what we garner from current “standard” measures, and how we might derive something that is a better match to what we perceive.
In your reverberation article, you said:
A strong direct field will produce an EDT that is less than (steeper slope) than the T30. This is a desirable attribute for increased speech intelligibility or music clarity.
Yes and no. “Increased speech intelligibility or music clarity” from reflected energy is dependent on the absolute level of the direct sound, the time gap between the direct and reflected energy, and the ratio of reflected energy that is merged with the direct sound regardless of frequency and the location of the reflection(s) compared to the energy that is not merged into the foreground sound stream.