  We present a comprehensive seismic study of the three pulsating stars of
$\beta$ Cep/SPB type: $\nu$ Eridani, 12 Lacertae and $\gamma$ Pegasi. Models
with the modified mean opacity profile are constructed in order to account for
both the observed frequency range and the values of some individual
frequencies. To decrease the number of possible solutions, we make use of the
non-adiabatic parameter $f$, whose value is very sensitive to subphotospheric
layers where pulsations are driven. This complex seismic modelling show the
need for a significant modification of the opacity profile.
