I think it is possible to include two random effects seperately (one for speaker and one for time) using lme()
by the following code:
x4 <- lme (DV ~ IV1 + IV2 + IV1*IV2, data=a.frame, random=~ speaker + item -1 | id),
with id
a higher level variable in which both speaker
and item
are nested. If you don't have such a variable, you could introduce it as a new variable with value 1 for all observations.