During recent years, solar seismology comes into a new era due to the quantity and the quality of data. In particular, data sets spanning a solar cycle or an important fraction of this cycle become available, allowing a seismic investigation of this magnetic cycle. However, despite some interesting results, this investigation has to face serious limitations. On the other hand, some new analysis techniques in helioseismology provides unexpected and spectacular results on magnetic regions, maybe opening a new way to the understanding of the magnetic cycle.