Figure 3: Perception threshold for the two tested groups.
(A) For each test frequency, the subject performed 50 trials changing the amplitude of the target stimulus according to a stochastic approximation staircase (SAS, see text) targeting 85% detection threshold. The perception threshold was chosen as the amplitude of the 51th stimulus as calculated from the SAS. (B) Generally, the osseoperception bandwidth is 100–1500 Hz, with 3 out of 12 subjects perceiving the stimuli at 3 and 6 kHz as well. The lowest perception thresholds (i.e. the maximum sensitivity) were found for the upper limb amputees (UL, right) at 100 Hz, being around 20 mN peak to peak. LL8 was excluded from the statistical analysis as identified as an outlier. *indicates p < 0.05.
