here is some sample to move the selection along the words and underline them
as the selection moves underlining is bit irrelevant
this in no way takes account of the speed of the speaking but that should be able to be adjusted to suit
vb Code:
Do
Selection.MoveRight Unit:=wdWord, Count:=1, Extend:=wdExtend
Selection.Range.Font.Underline = True
t = Timer
Do Until Timer - t > 2
DoEvents
Loop
Selection.Range.Font.Underline = False
Selection.MoveRight Unit:=wdWord, Count:=1
Loop
position cursor at beginning of text before running