Rand & LTT have not "begun" to combine, since they are the same person, and as Rand says at the very end, they always were the same person. That "combination" such as it was, reached its climax in the final chapter of tGS. Rand seems to think he won't hear the voice again, now that he knows it was simply his own mental efforts to reconcile his LTT knowledge. Now that he accepts he is LTT and RaT, he has no more need for that crutch.

My point EXACTLY. The viewings were from Min's point of view. So she sees them as separate people in Rand. Two distinct voices. Two PERSONalities. Now they have combined to ONE person. One voice. One PERSONality.