Do you tear up when you hear another person's voice quavering on the edge of crying?

I was just listening to NPR’s “StoryCorp”. There was a woman talking about her mother or grandmother and how great she was and how she will be missed and as she described the situation, her voice was quavering. You could tell she was either crying or almost crying and, involuntarily, I started to tear up. I was doing something else and didn’t even hear all of what she said. But I heard the sound and quality of her voice and it put me near the edge. Why?

Does this happen to you?
What is it that makes us do this? The frequency? The low level pattern? Why would we do this?