High modulation detection thresholds signal poor temporal representation of those rates.

Evidence

For illustration, Figure 5–11 shows how this task would be implemented using a 2I–2AFC paradigm. Here, a listener is presented with two intervals: one that contains a modulated stimulus and one that does not. The listener selects which of the two intervals contains the modulation. Listeners having difficulty detecting modulation will need more modulation to detect it, therefore requiring a larger modulation depth (m) at threshold. Higher modulation detection thresholds would indicate difficulties following the changes in amplitude over time, compared with lower modulation detection thresholds. We could also interpret this result to indicate that the modulation rates associated with high modulation detection thresholds are not well represented in the auditory system. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 1008