A distinction must be maintained between the stimulus (an external thing that can be directly measured, such as with a thermometer) and the person's or animal's resulting pain perception (an internal, subjective thing that can sometimes be measured indirectly, such as with a visual analog scale).
Properly defined, the threshold is really the experience of the patient, whereas the intensity measured is an external event.
It has been common usage for most pain research workers to define the threshold in terms of the stimulus, and that should be avoided ...
One study showed that morning-oriented people have higher pain threshold for heat as compared to evening-oriented individuals.
[4] Prolonged exposure to sound at levels evoking pain can cause physical damage, potentially leading to hearing impairment and tinnitus.