Thy speech shall be low. The feeble cries of a people wasted and worn out by a long siege are intended. These cries would resemble those which seemed to come out of the ground when a necromancer professed to raise a ghost.
The Hebrew 'ohv is used both of the necromancers (Le 19:31; Isaiah 20:6, etc.) and of the ghosts which they professed to raise (1 Samuel 28:7, 1 Samuel 28:8; 2 Kings 20:6, etc.). Here the "ghost" is spoken of.
Thy speech shall whisper; literally, chirp (comp. Isaiah 8:19). The word used occurs only in Isaiah.