Hmmm... this is interesting.
The Voices of the Catalyst
At the ending of the game when Shepard speaks with the Catalyst you may notice the unusual voice of the Catalyst. The Catalyst actually has three voice actors and this is easier to notice if you listen with headphones. In the left speaker the Catalyst has the voice of a Jennifer Hale (Female Shepard), and in the right speaker you can hear the voice of Mark Meer (Male Shepard). The child voice is played in both.
So Catalyst is speaking to you in a weird voice that includes your own voice fed back to you?
That very much sounds like a clue to it messing with your head.