Wallace and Joseph suppose that the first change is a natural sound change that can be seen in many languages (Spanish "hijo" 'son' from Latin "filium" 'son' ), which in Faliscan affected only a few possible candidate words. The second outcome cannot be explained as a sound change and so they argue it is a hypercorrect form caused by the other development. While the change from "f" to "h" was taking place and awareness of the correct forms was being lost, some speakers started restoring "f" even when it was not etymologically appropriate.