I wish this forum wouldn't constantly redefine well establish audio terms. Decay is the natural trailing off of sounds via ambiance or added reverb in a recording. A great IEM will allow you to hear it until the next louder sound masks it. A good IEM replicates the waveform with driver movement. No more, no less. Anything beyond that is overhang or overshoot and undesirable. Bass can be about right, overdamped and underdamped. Neither of the last 2 will perfectly reflect the signal.
Edited by goodvibes - 1/23/14 at 7:59am