Using 'talk at' usually implies the speaker doesn't allow for a two-way conversation or response. During the meeting, the boss just talked at us without taking any feedback.
Pro Tip 2/3
Negative Connotation
'Talk at' often carries a negative feeling, suggesting the listener may feel ignored or undervalued. I felt so frustrated when he just talked at me.
Pro Tip 3/3
Not for Dialogue
Avoid 'talk at' if you want to indicate a positive, engaging conversation; it's not suitable for that. She wouldn't talk with me, she only talked at me.