threshold of tickle

5.61  threshold of feeling; threshold of tickle. For a specified signal, minimum time-average sound pressure level (see A3.15) of that signal at the entrance to the external acoustic meatus which, in a specified fraction of the trials, will stimulate the ear to a point at which there is a feeling that is different from the sensation of hearing. Unit, decibel (dB).

Annotation         Instead of the method of constant stimuli, which is implied by the phrase “a specified fraction of the trials,” another specified psychophysical method may be employed.