Viz speech cutting off early

[Enlil]

Hello,
I am having a problem with a vizact.speak - initally, we called the speech in question in the following fashion:
def speechsample():

action = vizact.speak(audiofile, threshold = self.sp_thresh,
scale = self.sp_scale, sync = self.sp_sync, morph = 'business02_f_highpoly_talk.CMF' )
female.add(action)

However, from time to time, the speech would get cut off (in this case, 'please continue' was clipped to 'please cont'). So, thinking that perhaps the speech was being interrupted from a delay caused by loading the .wav file immediately before using it, we changed to the following code:
At startup, we run
action = vizact.speak(audiofile, threshold = self.sp_thresh,
scale = self.sp_scale, sync = self.sp_sync, morph = 'business02_f_highpoly_talk.CMF' )
Then later, we use
def speechsample():

female.add(action)

Any idea what is going on?

Thanks,
Christian