  We present results of pulsation analyses of B-type supergiant models with
masses of $14 - 18 M_\odot$, considering evolutionary stages before and after
helium core ignition. Using a non-adiabatic pulsation code, we compute
instability domains for low degree modes. For selected models in these two
evolutionary phases, we compare properties of pulsation modes. Significant
differences are found in oscillation spectra and the kinetic energy density of
pulsation modes.
