Thresholds are statistical detection probabilities, not absolute cutoffs

Evidence

It is easy, but a mistake, to assume that stimulus levels above the threshold always yield detection and stimulus levels below the threshold are undetectable (or inaudible). Rather, the term “threshold” usually refers to a sound level associated with a somewhat arbitrarily chosen percentage of detections, like 50% or 75%. For any psychoacoustic task, there is a range of stimulus parameters for which performance is between 0% and 100%. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 284

Categorization

• DEFINE: Clarifies that ‘threshold’ is a probabilistic detection level, overturning the intuitive all-or-nothing picture.