  We numerically study two methods of measuring tunneling times using a quantum
clock. In the conventional method using the Larmor clock, we show that the
Larmor tunneling time can be shorter for higher tunneling barriers. In the
second method, we study the probability of a spin-flip of a particle when it is
transmitted through a potential barrier including a spatially rotating field
interacting with its spin. According to the adiabatic theorem, the probability
depends on the velocity of the particle inside the barrier. It is numerically
observed that the probability increases for higher barriers, which is
consistent with the result obtained by the Larmor clock. By comparing outcomes
for different initial spin states, we suggest that one of the main causes of
the apparent decrease in the tunneling time can be the filtering effect
occurring at the end of the barrier.
